I have a '91 gta 305tpi. Since I installed a comp cam, the idle sucks.
Have checked and cleaned iac.
New plugs and wires.
Check fuel pressure(48 lbs)
Checked injectors(changed one bad one)
Used fuel injector cleaner.

Only when it is warm that the idle goes bad(idles up and down and eventually stalls).
But when I have the defrost on and the rad fans on, the idle does not go funny?
What gives? Do I need to check the coolant temp. sensor?

Any ideas?

LB9GTA

 

What is the idle rpm set at, do you have a stock chip or did you change yours for the mods you made. I have mid mods done to my car and the stock chip did the same thing as yours, got tired of it and got a Hyperchip from summitt, problems solved. My motor also like more fuel, I'm set for 55 with vacuum off. My experience with my car for tuning, setup as stock, teak for performance. Right now I am OK, but a dyno testing day is in the future.

 

Idle in drive is 500 and in park is 600.
I tried the Hypercrap, and it is even worse! I have documented 2 tenths slower in the 1/8th mile with the Hypercrap and the idle is terrible.

 

Sorry the Hypercrap didn't help you, if your chip isn't programmed for your setup, it willn't LOL. I don't know anything about your setup so it is hard to help you. As for 500rpm in drive, my car will not stay running either. Your problem doesn't sound all that difficult to resolve, check and varify minimum air flow, idle speed, timing, TPS, etc. And if that doesn't fix it, deal with it or I hear the GM services guys are pretty good at taken your money.