As I'm a newby to this sight please heed my words with a grain of salt (I may have no frickin clue what I'm talking about).
To reiterate:
-You have a slight fuel leak.
-Your having warm temp running problems.
-There are sweet/sour spots in your gas pedal (more dependant on deppresion of gas pedal or rpm?)
It sounds like a fuel return problem to me. The fuel system in most injected vehicles has extra fuel return systems that take heated unused fuels from under the hood and returns it to the tank to warm the tank fuel for better mileage and performance. It is heat and vacuum powered. So beyond changing all of your sensors which you already have, check all vac lines for leaks, and blow out all fuel lines to and from your gas tank. (The mess on top of your gas tank may mean it's not air tight and doesn't create the vaccum circuit needed to run properly. Try regumming around these plates that have the hose connectors on top of the gas tank?) And because it works fine until warm there is a valve that opens at running temperature that is connected to a faulty hose, possibly.
You also mentioned that you have trouble code 12 in a loop with an intermittent engine light.
The shop manual says....caused by
-Ignitioncoil to ground and arcing at sprakplug wires or plugs.
-main relay to power supply circuit is faulty.
-poor matings of power supply circuits connections.
-Check engine light wire to ECM shorted to ground circuit.
-ECM power grounds are poorly connected to intake manifold.
-Check for electrical system interference caused by defective relay, ECM driven selenoid, or switch. Can cause sharp electrical surge. Normall occurs when faulty system is operated.
-check improper installation of electrical options such as lights, wireless control, etc.

These are two different problems, in my opinion, a check of your HUGE stereo and other electrical components that may have been fudged while you were working on your rough ignition maybe the problem.
Otherwise, if all else fails, like it did so many times with my renault... get a 26 oz. of rhum, a good cigar, and sacrifice a small chicken to appease the engine gremlins.
GOOLUCK!

Interesting post....but I like your spunk. I thought "code 12" was simply FRED saying...."Hello, I'm here and I'm working but I aint got nothin' to tell ya". Maybe I got the code number wrong but the only code I get is the one that is supposed to come up first just to let you know FRED is operational and then trouble codes will follow that. But thanks for making me sit up and pay attention. I will definitely double check.....

code 12 is 'nothing wrong'...just that you mentioned intermittent engine light...so I quoted the holy shop manual.
That's what it says to Code 12 (in a loop) - intirmittent trouble light...
Maybe there was some confusion on my part...I had been assembling vaccuum hoses with a bit of liquid courage that night. The good news is noone got hurt....'cept some malt beverages!
If it is a hose problem ,fuel or otherwise, hooking up air to blow them out is a good way to check for leaks (with a windox bottle of water - to spray on the outside -you know yada yada), if not to clear them of crud... but if I'm just preachin' to the choir (who quite possibly knows the scriptures of the holy shop manual better than I) then I'll just shut my beerhole.
The gas line/tank advise is something my FRICKIN" FRENCH THING Renault Fuego taught me the hard way ...
It's not like I'm one to talk about vaccuum hoses. I've got a shop manual, Haynes, and several parts blowups and I'm still asking for help!
Let us know what it was when you got it figured ... Always useful to know!
<img src="/forums/images/graemlins/cheers.gif" alt="" />

Just in case people seeing the last two (or any) of my posts have had some concerns about my ineptitude....I assure you, it's there. I seem to nurture it daily. Or so I'm told. (though I don't always listen to THOSE voices)

Here are some strange things that (suposedly) matter I've heard along the way... (i dunno if these apply to Isuzu, they never have to mine). But when the logical is exhausted then only the peculiar remains. It is then that a voice inside of my head says 'now I've seen it all!'
These (useless?) issues I'll suggest 'cause everything else seems to have been done, or suggested on this particular dilema so far by persons more qualified than me, yet problems persist. Problems often persist because of the stupidest things not even an expert would expect. But I'm not an expert AND I've been known to do stupid things so perhaps I expect different things than most...

FINAL WARNING: I'M NOT AN EXPERT MECHANIC


-sometimes problems seem to be operating temperature related, but are merely coincidental. some problems are vacuum or electrical (as they build up too). Have you done emissions/electrical and hose/components testing when your vehicle is both warm and cold?

- different elevation, humidity, and outside temperature changes (if your destination from a cold start takes you through these changes) can play strange games. Do elements play a role? I don't drive where you drive (lucky you!) but if my ears pop over a hill AND my vehicle acts wierd at the same time (after I've exhausted every option), I'll take notice. (Or I'll look for the mothership! But my stereo has to act weird at the same time too.)

-some vehicles don't run correctly if the fuel cap (or fuel intake to tank) is not tightly sealed. (This is how my friend's chevy told him he had forgotten his gas cap at the gas station.)

-some vehicles, if all exhaust components are not in the right order, direction, or are even customized (thus changing outward flow) don't run correctly. (or like some Volvos, don't even start!)

-are your tunes the problem? One buddy of mine had so much audio power in a late '60's Chev truck that he would literally shake the components under the hood apart, and no matter how much lock-tight he used...tightening bolts was a monthly ritual! (Thankfully he only had so many hoses and contraptions under the hood. For his sake it wasn't near the spaghetti-fest modern vehicles have!)


So there you go ... I've laid out some obvious and some oblivious...
I'll shut-up now and wait to hear what the cure was.

Cause I expect some weirdness when I finally get my trooper back on the road!

Just an update on parts replaced and symptoms...

Changed ECM with known good one. Still no "Check Engine" light, therefore no codes but engine still runs crappy.

Changed Coil thinking that was easy, a possibility, and I'm waiting on the gaskets for the Throttle Body Assembly anyways. Wasted $50.00, no change.

Ohmed MAF and got good reading.

Next move will be to change the throttle body with TPS. Check all lines & valves (as has been suggested to me and I've been chipping away at a little at a time), and change the Fuel Pump Assembly just cuz it's bad and I got one on the way.

The symtoms have gotten considerably worse. Now on cold start the engine sounds a bit better just due to higher RPM but the skip is quite noticeable. Instead of it running great for the first couple of miles/minutes, it runs crappy within 30 seconds and idle is extremely irratic. I have been reduced to pulling over with my emergency flashers on so as to let others pass me cuz there are no more "happy spots" in the pedal. It feels as if there is something cutting off a cylinder or two intermittantly, and then maybe so much fuel is not getting burned that it is running too rich to go. The feeling is physical and it jerks me back and forth and I can feel the engine moving around under the hood as it struggles to do something but just can't pull it all together.

***Something worth noting is that sometimes while driving down the road I will pop it into neutral and the engine sounds and feels as if there aint a thing wrong with it but as soon as I put it back into drive....puff....back to being really, really sick.

It is primarily running extremely poorly now. It is with great pain that I have decided to park my "daily driver" and hoof it unless absolutely necessary. It's got enough problems without me making it worse.

OPEN for more suggestions...

Have you calibrated your current TPS?

Hey Phil....How do you do that? Calibrate the TPS? I'll look in my Haynes manual or check All Data if I can get to it today but I'd like to hear what you can tell me on that.

I'm gonna ohm it out today just to see what it says before I remove the throttle body but as far as I knew, you can adjust it by rotating it but I'm not even gonna go there cuz I've heard it's very intricate in its adjustments.

The throttle body assembly I got from a very good (new)friend from this forum came complete with the TPS and he said he's gotten it pretty much where it needs to be.

I would appreciate your comments though....maybe I'm way out in left field with the comments I just made...I'm flying blind with this stuff. Never messed with it beyond removing the entire intake manifold durring the rebuild and the throttle body was intact; nothing messed with.

dawn...

Here are the instructions mlclark posted in another thread:

It's really very easy to do, but you'll want an extra tps plug and several inches of the wires. I don't know how you might be able to access the TPS with your tester otherwise.

Thanx Phil. All that I,P, and ??? I know it only sounds confusing on first glance and if I take my time to read and absorb I should figure it out but I do have a brand new TPS with the throttle body so I think I'll try that first.

Your input is valued, as is most of the advice I've gotten thus far, and will go in my growing stack of helpful suggestions and instructions... <img src="/forums/images/graemlins/kewl.gif" alt="" />

So much to do and so little time to do it all... <img src="/forums/images/graemlins/rolleyes.gif" alt="" />
There are still so many things that have been suggested on this thread that I haven't had a chance to check/do not including what I've gotten from my research, my teachers, my buddies at Sanels, etc.

I shall return with an update though cuz I believe that with everything I do, and if I keep reporting the symptoms as they worsen, one of us will have that proverbial light flicker on inside our Isuzu brains that will finally pinpoint the little gremilin <img src="/forums/images/graemlins/evil.gif" alt="" /> messing up my ride...

I believe you can adjust it with the TB off the vehicle, which would also make access a lot easier, especially since Wayne has the double-jointed midgets tied up right now.

Don't worry, it's easy. You'll see. I guarantee you that you're far more competent at wrenching than I'll ever be. <img src="/forums/images/graemlins/kewl.gif" alt="" />