Quick question. 97 Z28, no vacuum leaks, did a smoke machine to test. When I come off the gas I have a high idle, (anywhere from 1500 to 2000 rpm's. So when Im sitting at a light its sitting at 1500 rpm's. I tap the gas once real quick, it revs then falls to normal (900-1000). I have to tap the throttle each time when I come to a stop to bring the idle down. I had the TPS and IAC scanned a couple weeks ago both work fine. Like I said no vacuum leaks. I think the IAC housing or TPS housing are just dirty and need to be pulled and cleaned. Im building a 383 stroker soon, and I will probably just buy a 58mm throttle body w/ both sensors if I can't resolve this problem, but I wanna fix it b4 I do the engine swap so I can't blame it on heads and big cam. Any ideas???

 

Clean the TB, including IAC and its passages. Re-evaluate.

 

Should I pull the whole TB off and all sensors, then fully clean it?

 

i would its 4 bolts and either to clean in your hands.

 

The simplest thing to check for is a kink in the throttle line. When i took my intake off the first time I had a similar problem. I tugged on the line and it was binding a little, once it was straight it fixed the problem.

would be nice if that is all it is