Depending on the engine code/ model year, I would say Idle Control Valve/ Throttle Body needs stripped and cleaned and the idle speed re adjusted. Sounds like the throttle butterfly is sticking, and causing a stall. Check that the connections on the air mass meter are tight too, they have been known to be broken or loose causing problems, but that usually brings on the engine management light. Hope this hepls.
Spannermonkey
May 2010