High idle in Neutral or Park

[98SF19]

Yes, I am posting this without searching the forum. GUILTY!

The issue arose tonight as I was sitting in traffic. I had put the car into neutral and after a few seconds realized that the high revs were coming from me! Shifting to drive or reverse brought them down. The issue continued when I got to my destination. It went away later after stopping off somewhere else to watch the debate (Rubio tore the Chump a new ********!). I checked for a code earlier when it was still high, but got nothing. Is this most likely the IAC sticking? I hope so cuz I've had a new one for a while. FWIW, the motor started much stronger than normal at the beginning of it all, and this was after the car had sat for a few days. Also, I replaced a rear coil last weekend. Hopefully, the issue won't return, but if it does, I'd like to know the most likely cause.

Thanks

 

[Nuke]

I would start with the IAC if there was no codes. Try cleaning it with some B12 or carb cleaner. That seems like the most likely culprit.

I will say I had this issue a few weeks back on my Jeep. Thought it was the IAC. When it finally threw a code, I read it, and it turned out to be the TPS. Replaced that, and haven't had any more issues.