The problem started when we got a snow storm the week before Christmas. I was stuck in traffic for over an hour not going more than 10 mph at a time. My voltage meter kept going down and the car was running a little rough but never died and the voltage never got to the red, stayed between the middle and red. I parked my car and left the next day for over a week. While I was gone my boyfriend tried to start the car and it wouldnt start. Still had juice, lights and what not worked. When I got home I started it and it started just fine no stalling nothing, voltage went up and everything. I turned it off and later went back tried to start it and nothing. Wouldnt even try to turn over at all, again all lights and everything worked. I started it again the next day let it run to temp and defrosted it and all that, turned it off and when I tried to start it again, nothing. I thought it would be the alternator but I am getting plenty of power it just wont start 90% of the time.

Check the FYI section (It's new!) under CPS, or Crankshaft Position Sensor. Does that sound like your Jeep?

You might want to check your battery also.