I think it may be associated with the fuel pump. My car would sometimes start and sometimes not, has done it since I got the car two years ago. I finally noticed a couple weeks ago that when I turned the key I didn't hear the fuel pump kick on for a sec and shut off like other cars do. I flipped the key off and on a few times and I heard the pump kick on and the car would start. Now when I get in it, I turn the key on and see if I hear the pump, if I don't hear it, it will not start. I have to flip the key off and on a few times for the pump to come on. I found there is a fuse with poor contact in the under hood fuse box, if I wiggle it the pump will cut in and out. Your jeep may be doing something like this. If it only happens sometimes, it sounds like something is loose and making poor contact. Probably a easy fix but hard to find. Next time it wont start I would start wiggling things to find the short, your gauges should come on when you find it.
