I just had my LT1 rebuilt last year. Everything is all new. It got a mild cam, heads were gasket matched and reconditioned. Ive had a problem problem with an high idle and cant seem to figure it out. I had the pcm tuned, repaced the IAC, and have checked all over for vacuum leak and cant seem to find any. Now to top it off the exhaust is popping and has a little misfire.
Any help would be appreciated

 

Have you done a scan data log to see how the IAC "counts" are responding to the high idle? Have you checked the throttle stop screw to make sure it's not keeping the blades open too far? Checked the throttle cable to make sure it's not hanging up?

Excellent free (for 20 uses) scanning software..... you scan it, we'll review your data log:

TTS Power Systems