Hello here's the specs 355 77 truck block converted to roller lifters, tpi ported with stock throttle body(stock air box), lt4 hotcam, edlbrock performer heads, using an ostrich, 2200 stall with 700r4, 3:42 rear end. I've had it running pretty good this summer (2 sets of rear tires later), I've raised the idle to about 900rpm. However I will get it idling good then run it hard and the idle seems to change when the car heats up alot starts to bog the idle slows to 600rpm. I can make it idle better again by reloading the bin. Just want some opinions if this is a sensor issue (I've reset the IAC alot but never changed it) or if it sounds like a vaccuum issue, anyways any helps would be appreciated. thanks in advance