Gonna start replacing parts tommorrow,I'm not sure which module to start with.If anyone has advice,I'd appreciate it.

The first place I would start would be the coil. You can meter that to see if it is shorted out. Also make sure that you have power to the coil.

Thanks,Grey88.I'm pretty green at auto repair.

also may want to check the crank sensor and pickup coil in the distributor, crank sensor first. Very common problem with 4.0L. Go to this site and download 88 shop manual.
http://www.lunghd.com/Downloads_and_Links/Downloads.htm

I should have mentioned that this is an intermittent problem.If the jeep cools down for a while it will start and idle but will only drive a couple hundred feet before it dies without any notice or noise-just shuts off .

Crank sensor it was-Thanks,89LTD,you got it on the nose.