99 Grand Prix GTP problem

[jtckf]

My sons car..
The engine cuts out every so often. At idle, it revs some on its own..
what I've done,
1. new plugs and wires ( which needed changed anyway 131K)
2. all new coils
3. new gas cap
4. the supercharger was rattleing, so we just changed the coupler..sound is gone now...coupler was deffinately worn

but now back to why is the engine cutting out..Any ideas????

 

[tomc]

Have you checked all the vacuum lines? there is one under the MAP sensor that may come loose. Had the problem for about a month before I tracked it down. 99 GTP - All stock 249K and driven 70 miles a day to work and back.