Idle Problems

[97chevy350]

I was sitting at a light this morning and I felt the engine start running really rough. I looked down and the rpm's were at about 500. I gave it some gas to keep it alive until the light changed, then I started to go and it ran really rough with little power for a few secs then seemed fine. It did it again at the next light but not as bad, and by the third light it was running plenty smooth but was idling at only about 500 rpm. Another thing i noticed the other day, it seemed to be idling a little fast. It doesnt seem to fluctuate so I dont think it is the idle air control. What is goin on?

[Bish]

I was sitting at a light this morning and I felt the engine start running really rough.  I looked down and the rpm's were at about 500.  I gave it some gas to keep it alive until the light changed, then I started to go and it ran really rough with little power for a few secs then seemed fine.  It did it again at the next light but not as bad, and by the third light it was running plenty smooth but was idling at only about 500 rpm.  Another thing i noticed the other day, it seemed to be idling a little fast.  It doesnt seem to fluctuate so I dont think it is the idle air control.  What is goin on?

 

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Not sure if your TB is the same but my Idla Air COntrol valve was covered in crud when I had a similar symptom. I pulled is and cleaned it with Throttle Body cleaner and the problem went away. On my 01 Tahoe, the IAC is mounted on the top right of the throttle body.

[97chevy350]

Took it out and cleaned it up, at first it idled at about 1500 for a few secs then came down to about 900 and stayed steady. I took it around the block and came back, idled at a steady 750-800. I think I should be alrite now. Thanks alot

[97chevy350]

Thought the problem was fixed, I was wrong. It did the same thing again last nite, but only after I had run the truck for a little while. What should I do now?

[redvett]

Start looking for a vaccum leak. You can use propane torch (un lit) or WD-40 to go around intake and any vaccum lines & throttle body and see if engine at idle (warm) starts to increase RPM's. That would indicate a leak.

[ridnlow]

could also be dirty fuel filter or bas gas..

[97chevy350]

I put the fuel filter on about 3 months ago when I put the pump on, and I doubt it is bad cuz b/c i have been running sunoco 94 to keep up with the pcm tune. I even ran some lucas through b/c it still pings a little. I think the gas everywhere is of less quality recently.