new to the forum. 01 1500 sport ext. cab, 5.9 auto. idle problem to start, removed throttle body, removed iac, tps, and map sensors, thouroughly cleaned tb, replaced base gasket , replaced with new, the TPS, IAC and MAP sensors. now when cranked cold, iac whistles and going down the road under hard acceleration it whistles also. any help?

 

Recheck the o-ring on the IAC.

What about the gasket under the air box? Is that still in place? Did it seat correctly when you put it back on? (they are a good source of strange air-flow noises.)

Welcome to DF!