ok so, my truck does not do it all the time but heres what happens:

only when its warm, but not alll the time when it is warm, my engine makes a squeeling noise like it has a turbo (which it does not, unfortunately). it reacts when i increase/decrease the throttle and is defintly NOT my tbs whistling sound. It doesnt seem to affect anything but it incredibly annoying...

 

Have you tried looking under the hood when its running and revving the motor up. Could be a bad pulley, tensioner, or alternator.