Originally Posted by a burrito
In response to your "other thoughts" i think that some thoughts are comflicting to the Stage 2 filter itself. I too have the Stage 2 filter + MS Pulley and the car started running slightly hotter after the Pulley's, not the filter. The stalling doesn't seem normal at all and I doubt the filter is making your car stall. You should get that checked out.
Yeah, I agree that it is most likely the pulley. I read somewhere that a pulley can have this effect.
As for the idle, I believe that it is related to the tune. It only happens when the engine is very cold - a brief throttle blip will remedy the issue.