2002 Jeep Grand Cherokee - Stalling / Won't Start

2002 Jeep Grand Cherokee
4.0L V6 - 4WD
101K miles

Main cause is that car "stalls" frequently while driving - by stalling, I mean that sometimes the RPM will drop to zero as if the car lost power, then start back up 2-3 seconds later.  Other times it will drop to zero, then require turning the key to start the car again.   I can be idling, or I can be doing 50mph.  Doesn't matter.  Brief history of the last couple days:

Friday - car felt like it lost power a couple times, but always started up on it's own.

Saturday - car actually stalled a couple times, but started right up when turning the key.  

Sunday - same as Friday

Monday (today) - shortly after leaving for work... two complete stalls requiring me to restart the car, then the third time, the engine wouldn't even crank.  Nothing.  Had it towed home, noticed that the Jeep rolled off the tow truck even while in park.  Shifted in and out of park a couple times, finally parked, and Jeep starts again now.  

Neutral safety switch??  Would that cause a car to stall out while driving by causing a short in the system at all if it's bad?  

My other thoughts are a bad relay... or worst case the ECM going bad on me.  Any thoughts / suggestions would be most helpful...  I'm a novice mechanic, everything I learned was from hands on experience and internet research.

Charlie

[discretesignals]

Have you checked for trouble codes?  If so, what are they?

Neutral safety switch won't cause stalling, but can cause a no crank if faulty.

Make sure the battery terminals are clean and tight.  Jeep electronics act funny if you don't have a good connection at the battery.  You should also have the battery load tested.  If the battery tests good, be sure the charging system is operational.

Another possibility is a faulty ignition switch.  To verify, you would have to check for power going into and out of the switch when the problem occurs.

[theturds]

my 1997 Jeep Grand Cherokee has been having the same exact problems , except today when i tried to start it , it back fired and exploded my muffler. i have recently changed the crankshaft position censor( today actually) it wasn't till then when it started running this bad.

also changed the spark plugs and added some fuel injection cleaner new battery. please help if you have any other information on this