IAC Issues 97 Tahoe

[leatherbee]

Have 383/roller cam/roller rockers/full lenght headers/Dart heads, etc...Had Westerns tune PCM...Also have converted to the electrical FIs from the poppets....

Idle stumbles for the most part and sometimes runs allright. I stuck a new IAC valve in there with no luck...When I firsted started the truck (cold) and got the idle to stabilize I unpluged the IAC...The truck now runs fine (no stumbles) but obviously the idle is to high when it warms up.

I think it is a faulty PCM...The computer cannot control the idle properly??? However I can control the idle from the scan tool when the IAC is plugged in...I have called Westerns to send a new PCM...Anyone seen this? I have tried reseting the IAC as well

The other issue is that the knock sensor will detect knock even at no load when I rev it...I did replace it and made sure it was torqued properly with no luck....I think this could be caused by one of the non stock parts---cams, pistons, headers....Do they make a aftermarket
one that will not detect false knock or is there a way to bypass it so my timing not getting retarded???

Lastly it may be normal because of the cam....503/.510Lift 288/290 Dur....But I pick up misfires on the scan tool at a idle only (no load)---not alot and I get no PO300 codes---The engine runs nice in closed loop and I have smoked tested for vac. leaks....Is this normal for a somewhat radical cam????

Has anyone else had these problems...Any help appreciated...Sorry so long...