I have been fighting this issue ever since I put in a new cam. Specs are: LS 402, ported L92 heads, 230/233 114+4 cam, bw s482 turbo, holley hiram intake, nw 92mm cable tb, 2002 pcm.
Trouble is it seems as if the IAC isnt big enough to cover the whole range of engine operating conditions. For instance, if I have the blade screw opened up enough so I dont have to give it pedal to start, it will not idle down (IACP=0) and pulls timing in an effort to reduce engine speed. If I close the blade enough where it has control when hot (IACP>0), I have to give it roughly 10% throttle for the first few seconds to keep it running.
Any suggestions? This is very frustrating.