2001 Other Jeep Models what could my problem be?

Next time it refuses to start do below-

Get a carb cleaner and spray into the carb or the throttle body on an EFI. Did it start and die? If not disconnect a sparkplug wire or 2 and ground it to the engine -have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel problem, check the fuel pressure to rule out the fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light.

Fuel pump/Pressure Regulator/Filter and Injector/s checks out-start checking the ignition system-power to coil, coil/s itself, distributor pick-up, control module, Cam and Crankshaft sensors.

If both fuel and spark is present-check the valve and ignition timing, this will lead you to problems with compression and valves opening and closing at the wrong time

Check with the local DMV if its stolen then go from there.