I have a 91 Z28 355 cid auto. This problem just started. When I stop at a traffic light The car idles fine for a few seconds then she will hunt from 500->800rpms. I have to touch the gas to level the rpms off. Then she runs nice for 30 seconds then hunts again. The car drives good and doesnt seem to miss at all. This only happens in the drive gears and not in park or neutral. Any ideas?

 

seems to be somethin that plagues all thirdgens for the most part. im interested in the answer as mine does it too.
fuel, electrical are all up to date and functioning properly, no vacuum leaks seem to be there. so i am confused.

 

Dirty IAC normally on a stock car..

The Stall saver code sometimes has issues too. On my car I had to raise the idle to 800rpm to compensate for the cam.. (in prom).

Try cleaning the IAC..

 

any recommended method to cleaning the IAC?
does it have to be removed to clean or can I do it right on the engine?
thanks alot!
thats one thing i havent tried doing to fix the problem

 

Yeah gotta removet he throttle body, dissasemble the bottom section, and clean it with carb cleaner..

-- Joe

 

They're probably right but when is the last time you replaced your O2 sensor?

 

well not since ive had the car no replacement
how much do they cost?

 

In the $30 range I believe

 

thanks alot Dan!

 

Well. That is possible.. At least after the car warms up anyway..

 

My car is far from stock and this problem only just started and is intermitant. Thanks for the advice! I will clean the IAC when I install my Holley AFPR and will put in a new O2 sensor just as a maintenance thing. Thanks for the input and I will let you know what happens.

 

Hey Anesthes, Got pics? Would love to see that car...

 

I've got some old ones..

http://members.cisdi.com/~anesthes/projects/pix/

Whats different is, the gauges are in a a-pillar pod now, the engine bay is cleaned up big time, different valve covers (M/T alum), formula wheels, and a few other cosmetics..

Thanks!

-- Joe