1999 M3 squeak on left side of engine

[kdubois]

Hello,

I am trying troubleshoot a difficult to isolate squeak. It is coming from the left side of the engine near the alternator. I have used a screw driver to listen to the alternator, but I can't hear the squeak through it. I have replaced both the idler pulleys and the belt but the squeak keeps coming back. It only happens once the engine is warmed up and it isn't a constant noise but seems to sound like squeak, pause, squeak at about once or twice a second and goes away if I give it a little throttle. Any help would be appreciated, thanks