Ok my iroc with a 350 TPI is idleing weird. When its in park or nuetral after I rev it or it sit's for a few sec it idles at 1500 RPM. But if the engine is under a load like when its in reverse or drive it idles around 1000 or 900rpm like it normally does. The rpm doen't jump or there isn't any hesation or any other problems. What do you guys think?? Maybe the MAF sensor or the throttle Position sensor?? I gave the MAF sensor a few hits with my hand and there was no change in idle. Also when I replaced my belts I never put on the smog pump belt. Could this be the problem?? is it bad to not have the smog pump spinning when everything else is hooked up for it??any info will help.

 

I gave the maf sensor a couple of wacks with my hand and there was no change. If the helps. I checked to make sure none of the sensor's got knock out when the alternater belt pop off. I didn't see any thing wrong or any vacuum hose out. I'm just trying to figure this out so my iroc will be squared away.

 

sounds normal or possibly a leaking gskt/vacuum leak..i've heard of a lot of throttle body base gaskets getting cracked..all the TBIs that i have ever driven when reved up in neutral would stay at about 1300 for a few seconds then slowly return to idle-800-900 just my 2 cents but i'd bet the base gasket

 

Just a thought in case it was overlooked; check the position of the trottle dial to the stop when you are idling. I had a similar problem and it was the throttle cable binding at the firewall.