Thread: Engine Power

I have the 3.8 6cylinder supercharge 1997 grand prix and seems when I stop at a light i notice my rpm will drop below 5 and the instrument lights get dim and when i take off everything is fine and when I stop it happens again. Got a new battery and alternator during the fall of 2011. Seems when I cut out the supercharger on the engine its fine has anybody else had a similar problem? Yeah I know " dont stop at the lights"