I have a 95 xj sport with a 4.0 straight six. I was taking my son to the baby sitters when my jeep decided to shut off. I noticed the volt meter going from 14v to 5v to 95v back to 5v and then back to 14v before shutting off. It then would start and run for 3 seconds and proceed to shut off again. I thought it was the alternator so i had it checked and it passed both times. now it wont even turn over. What do you guys think it could be?