I have a 98 with the 4.0 auto. Sometimes when its hot outside, my jeep will randomly just shut off. My check engine light isn't on. sometimes it will spit and my rpms will jump but only once at a time. I can't figure it out at all. What could it be? Seems to only do it when it is hot out or was a hot day.

 

if it starts back up it could be your fuel pump get a fuel pump pressure tester thingy and test the pressure shouldnt be lower than 31.

 

When you say it "will randomly just shut off". Does it give you any warning or does it shut off like you turned the key to off? If there is no warning I would testing the CPS. But I would first have it checked for any codes. Just because the cel doesn't come on doesn't mean you have no code.