[mikeC8]

97 Sierra K1500, 5.7 liter. High pitched whistling sound underhood in the vacinity of the throttle body. Starts after truck warms up and quiets down when accelerating. I've wiggled hoses, disconnected what I could without stalling engine, checked air lines into throttle body, checked air filter, etc. Sound does not change when I apply brakes so I don't think it's related to master cyclinder. The only time it changes is when I accelerate, then only gets quiet until I come back to steady speed.

Truck has 85,000, runs great. No codes.

I read some of the other forum posts about whistling but couldn't fine one with similar symptoms.

Any ideas? Thanks........Mike