As the series of the problems keeps on going:

Latly My 3.5 had been running very rough and vibratin around the low RPMs 1000-2500. And this is happening all the time even after the engine is in optimal tempreture.

It even gets wores as I trun On the A/C. I could feel the vibration through the 4WD Lever as it shakes.

My sparkplug have only 20,000Klm on them. And I use normal(not premium) Fule.

I have cleaned the Air Filter and I chekd the ISC motor(Stepper Motor) but I found nothing accourding to phsycal examineation(I found nothing wrong)

I hope it is not the betterfly Valve......

Any thoughts

Any help would be Appreciated

Come on guys 17 views and not a single replay or a thought <img src="/forums/images/graemlins/frown.gif" alt="" />

It has been a holiday weekend and maybe all the 3.5 experts are out getting hammered. Patience young grasshopper. <img src="/forums/images/graemlins/wink.gif" alt="" />

Try a search while you are waiting, your answer is probably already out there.

Doesn't the 3.5 DOHC call for premium gas?

My 95 3.5 dohc does indeed call for premium... 93 octane.

The truck has a knock sensor so it should retard timing if the cheap gas makes her ping.

It sounds like an idle air controll motor problem, but I don't know enough about the 3.5 yet to guess further.

Idle air motor will problems not make your car run rough. It only affects the idle speed. (too low or too high). Could be your butterfly valve. I believe it is in on position and then flips to the other position above a certain rpm.

I am betting on electrical. Your cheap plugs may be the problem. You really should have double platinum plugs in there. How many miles on your truck? How old are your wires?

What kind of plugs did you use? How many Miles on the truck total? have you replace the Spark Plug wires? Have you checked the coil packs? some things to think about testing..

well thanks guys for the input

Well I took my plugs from the dealer, and they are almost 20,000Klm old or a bit more( they are still not 1 year old )

about the wires: I don't know how old are they because I haven't changed them from the previous Owner along with the coils packs. <img src="/forums/images/graemlins/frown.gif" alt="" />

My truck has 192,000Klm on it( this is very Old)

How do I identify I bad butterfly valve?????
I did remove the air-hose to romove the ISC motor and I looked at the butterfly valve but I couldn't see anything wronge with at as far as I Know <img src="/forums/images/graemlins/confused.gif" alt="" />

I have tried to add A fuel Addictive(STP Fule injectors Cleaner)
and still didn't finishe the tank yet, but still with no improvments at all. <img src="/forums/images/graemlins/frown.gif" alt="" />

When I turn on my A/C it gets worse and the engine is like dancing( I could see it through the 4WD stick)

And if I rev it up the the engine it okay only past 3000-RPMs. so Only the low RPMs there is a problem

OK sorry. My bad. I was thinking of the butterfly valve on the 94 or 95 SR trucks. I see you have a 97 so there is no butterfly valve. I am talking about the butterfly valve on the intake manifold, not the one in the throttle body.

Once again, it sounds like an electrical/ignition problem to me. 8 year old wires is not good. Check the coil packs. Camshaft position sensor, crank position sensor.

The best fuel injector cleaner in a bottle is probably Chevron Techron.

How did the plugs look when you changed them? Any oily plugs?

How old is your timing belt? If it is original it may have stretched so much that your cam timing is off.

Have you taken a compression test? What is the vacuum at idle? Are there any codes in the system? Whats the fuel pressure?
Conner