I have a Jeep Grand Cherokee ZJ 5.2L V8.  Yesterday while out on the trail I noticed by passenger door mechanism was constantly 'unlocking' the door.  I figured something was loosened and didn't think much of it.  On the way home my radio deck started to intermittently shut off for a few seconds and then turn back on.  At the same time my headlights began flickering.  I made it home and figured I'd take a look today.  However; I guess I wasn't done being surprised that night.  I had it in park and went to reverse and everything shut off.  I put it in park and the lights came back to life but wouldn't turn over.  I attempted to put it in Neutral to start it and whenever I shifted out of park everything would shut down.  Anyone with any advice?