You may have a vacuum leak, get a can of spray Throttle body cleaner, spray the vac lines and maniflod area, when the idle changes, youve found the leak! You want the engine running and spray on the outside but do direct the stream onto the hoses, if it is a vacuum leak, the engine idle will change speed, then you have detected a leak, repair the vacuum leak and see how it runs! If that doesnt do it, you may need a new idle air control valve, it's bolted to the throttlebody. Try to keep the spray off the hot exhaust manifolds, it can cause a fire.

Answered by merlin2021 (expert)
18,145 answers provided

I would have like to think that checking for vacuum leaks would have been one of the first things done - especially at the dealership but who knows? I'll definitely giver it a shot. The dealership wanted to replace the IAC actuator but for $100 labor I figured I could undo three nuts and replace it myself which I did but to no avail. Is the idle air control valve different from the IAC actuator or are we talking about the same part. The part I replaced bolted on to a bracket mounted to the throttle body and had a plug with 3 or 4 wires with a plunger at the other end. Is there any way to test that part to make sure it's working properly?

Response from tkainz
2 questions asked