I own an 89 GTA 5.7L stock. Earlier this year my radiator coolant fan went out on my car which is when my problem began. With rising heat I figured that it just had made the transmission fluid coagulate or something, but once I fixed that the car still jerked when trying to slow down. At a red light it idles anywhere between 600 and 1500 RPM's. It's tearing at the transmission like insanely....Could it be my throttle body?

 

Try a search on "surging idle" and you'll come up with a lot of hits. Have you tried resetting the IAC via the factory method?

 

Reset it factory method...haha I can turn a wrench, but I don't even know where that is located man. I'll search both of them and see what I come up with. Thanks for the help