I have a 2000 Jeep Grand Cherokee Limited Edition it starts and runs good for awhile then just dies. It always says there's no key in the ignition when it starts this, help please?

Maybe the ignition switch is bad.

Check the wires going to the transfer case if it's 4x4. 3 wires going to a sensor on the outside of the case. If those wires or connections get dirty, wet, or loose power in any way, the engine will die completely and suddenly with no hesitation and will only start back when the connection is reestablished (when the water or dirt drips off).

A good way to test these would be to wiggle them around while the engine is idling. If it does, you've found your problem.