when my car is in park, and I tap the throttle, the engine rpm will dip below 500, and the oil pressure will reach near zero, and sometimes the battery and/or bas-asr lamp will flash.. most of the time the engine does not stall.. however, a similar situation occured while i was driving

one time when coming to a complete stop, the rpms dipped below 500 and the car stalled

another time, when i was creeping in traffic, the rpms dipped again and the car stalled

any idea of what could be wrong? maf or camshaft sensor of some sort? is the timing off?