Thanks for your suggestion. It solved my Dad's Jeep problem. Worked like a charm! $29 ignition coil from AutoZone. Disconnect negative able from battery 1st. It also requires both a 10mm wrench and socket wrench to take out because what's holding it together is a bolt and nut. I'd figure it would use Engilsh not Metric tools since it's an American car, but no - it was Metric. Becareful when removing nut cause you could easily lose it. Putting it back on wasn't that much of a problem - finger tighten it then use the wrench and socket wrench to tighten.
i think i have a solution to the famous stalling problem with the inline 6 cylinder 4.0 engine.
i was pretty sure that it could not have been the crankshaft sensor. but i did know that it had to be an electrical problem, dont worry it has nothing to do with the computer, pheww... so i replaced all the spark plug wires, all the spark plugs, the distributor cap and the coil. i thoght i had the problem fixed but i sure didnt. and the last thing i had in mind to replace was the ignition coil, sure thing after i replaced it i have not had any more problems woohoo i love my jeep once again!!!!
hopefully this can take care of yours, if not i guess you could be S.O.O.L but im sure you will find the answer