My accord has a high idle 95% of the time, every once in a while it will go back down to normal, but that's rare. Sometimes the idle fluctuates like the IACV is bad or dirty, but I've cleaned it twice now. The idle is high no matter what, hot, cold, or at N.O.T. I took it to a good reputable mechanic and he told me that it was the intake manifold gasket, so I replaced both of them today. Car seemed to idle fine, then I took it on a drive and it started doing the same thing. If I put it in neutral and rev the engine to 5-5500 rpm and let it drop, the idle will go back to normal. Please, tell me somebody has a friggin clue what this is. I cleaned the intake plenum and EGR port when I had the manifold off as well. No dice. Any help is appreciated, thanks!

 

$20 paypal'd to whoever has the correct solution for this problem

 

Not totally sure but I had a similar problem with a V6 Vectra. Turned out to be the idle control valve (or IAC valve as its sometimes known) removed and cleaned it and my idle issues went away. May be worth a google?

 

If you read, i've cleaned it twice and still no dice.

 

Just for giggles, let it re-learn idle.

Cool/cold engine. Pull the cables to clear the ecu/pcm. Connect it back up. Start the car with no engine load (ac, blower, radio, ect in the off position) and DO NOT touch the throttle. Let it sit there and run until the cooling fans cycle at least once. Cost to you is nothing but a small amount of time.