92 silverado camshaft

Have a 1992 5.7 litre silverado with a screeching noise from the crankshaft pulley when engine is warm and idleing. Noise goes away when engine is accelerated. Noise remains on crank pulley when serpentine belt is off pullys. Did replace tensioner pulley, alternator, and ideler pulley. No noise noted when started cold. Serpentine belt is only weeks old no signs of damage. Any suggestions? No rough idle or performance changes noted just a annoying noise similar to a turbo but only when no torque is applied.

It turned out to be the throttle body gasket leaking air which made that screeching noise. My mechanic found it right away after spraying brake cleaner on tbi intake. :loser: