I'm having some issues with my scoobie stalling. When I'm coming to a stop, off throttle with either the clutch in or in neutral, sometimes the RPM will fall all the way to 0. The idle isn't lumpy, but it will occasionally jump from the normal ~600 to somewhere closer to 1100rpm, then drop back down again. It's an 06 WRX stage 2 pro-tune with 95k miles. I thought it could be spark plugs (which I replaced with NGK ir back at 60k miles), but according to the manual it isn't due til 120k. I also replaced the oil on schedule and still have the same problem.
I should also note that the serpentine belt snapped recently when the pulley locked up. The tech replaced the harmonic balancer, pulley, belt, and pulley crankshaft. Would this have anything to do with it?