I have a 95 regular cab short bed pickup, 4.88's, dual cases, lockers front and rear. Anyways, I parked the truck for over a year and now it runs terrible. It has 170k miles on it, and ran fine when I quit driving it.

The truck seems to miss frequently at idle but straightens out when I get on the throttle, however it is really lacking power, exspecially on the highway and going up hills. The idle also likes to jump around sometimes, staying in a 1000-500 range at idle, I'm trying to set it to 850. It smells like its running rich and I have a lot of black soot coming from the exhaust. Its getting about 13.5 miles a gallon.

The CE light is on from an O2 code and this truck has a slight history of O2 problems. The wires for the 4 wire 02 fell and melted to the exhaust, ruining the connector for replacing it. I bought a new o2 sensor, soldered the wires, water proofed them the best I could. Truck ran great after that and I prolly put 40k on it since that incident but the O2 light never went off, even after resetting the computer by both unhooking the battery and pulling the efi fuse. Both of which I have done several times. Strange thing too is, it will spit out an 02 code before it even runs after a reset, it is almost like it doesn't even recognize its there. I say this because I have tested unplugging other efi components after a reset, plugging them back in and checking for codes, which the truck will recognize.

With the O2 being suspect for the poor performance, I have purchased another one, redone the wires again and it hasn't affected it at all.

Here is a list of other things I have checked.
-cap, button, wires, plugs...the plugs don't look bad, just a little soot at the top of the threads and they look like they might be burning a tad hot but not bad at all really.
-catalytic is clean
-TPS checks out, although I noticed the intake has a lot of gunk in it, but I figure this is normal for a truck with 170k.
-I have inspected the wires going to the o2 then best I can, removing the wire loom the factory wrap seems well intact.
-timing chain on the truck doesn't have more than 20k miles.
-compression is 155 in the best and 147 in the worst, pretty good I thought.
-stethoscoping the injectors, they seem to all be clicking and sound alright to me although I'm no expert on that, never had problems with injectors in any vehicle.
-can't set the timing dead on 5 degrees BTDC. I'm guessing this is because of the miss at idle, the mark kinda jumps around on the plate, I have it set as close as I can. I do have the jumper wire in while doing the timing check.
-I have inspected vacuum lines over and over can't find a leak. I have sprayed starting fluid around and haven't noticed a jump in rpms from this.
-replaced the fuel filter
-swapped MAF with another truck that was working properly, no change
-cleaned throttle body and made sure vaccum lines were clean and that the plate could close proplerly

Thats about all I can think of for now, although I might have forgotten to post other things I have checked.

I think I'm going to pull the intake off and clean it real well. Is there any way I can check the injectors after I do this? Or what is the proper way to check the injectors?

I'm really in need of some suggestions, I'm at wits end with this thing.

All I wanted to do was start wheeling again and put my straight axle in, which is sitting in my garage all ready to go and has been since I quit driving the truck.

I hope someone can steer me in the right direction here.

I have a couple of trucks I run once or twice a year also. The major problem I have is GAS. I was quite a skeptic about how bad this 1 year old gas really was until I sucked out the tank until it is under 1/4 full, filled it with premium, added 2 bottles of injector cleaner, and drove the piss outta it. That old gas will barely run my lawn mower....Good luck.

It was parked close to empty and I have run over a tank through it already, thanks for the response though.

Oh yeah, one more thing. I have seen the brake light come on a couple times, just for a second, at about 4k RPM. Doesn't come on everytime I hit that mark but occaisionally.

You made comment about dirt/gunk in the intake. I would consider cleaning the intake plenum and throttle body.

if the idle is varying and the timing cant be set, thats classic TPS sensor. www.4crawler.com has good instructions for adjusting the TPS. Also check to make sure the throttle cable isnt too tight, that can cause it not to enter its idle mode and makes the idle vary. if it cant go into idle mode the base timing wont be able to be set. for a more "real-time" reading, i take Idl-E2 measurements at the ECU, get an ohmmeter and some piggyback test leads, connect to IDL and E2, push the gas pedal and make sure when its closed, you get the .057 reading and when you push the pedal it goes to infinite. watch what it does when you let the off the pedal.

check here to see where and how to connect the ohmmeter. this is how i figured out mine when the throttle cable was too tight, years ago. make sure you use the proper section, one is 2wd and one is 4wd. hope this helps.