Excuse me for jumping in here. I read through everything very quickly and from what I see, the engine stalled, you replaced the coil, the engine runs for a few weeks, then it stalls again, is that right? How about if I reword it like this: the engine stalls, you let it cool down while you tried some stuff, then it ran again after it cooled down. I think you're assuming it was a bad coil because the engine ran after you replaced it, but what if the engine also ran after you replaced the wiper motor or brake light switch? What my meaning is, is the coil might not be bad.
The next time it stalls, if you have no spark, check for voltage on the 12 volt feed wire to the coil. On the cars that is the dark green / orange wire. Not sure of the color on the Jeeps, but you should find 12 volts on both of them for one second after turning on the ignition switch, then again during cranking. If that voltage is never there, there is a break in the circuit back to the automatic shutdown (ASD) relay, or the relay itself is bad, but that is very uncommon. It's more common to have 12 volts for that first one second but not again during cranking. That would indicate a failure of the crankshaft position sensor or the camshaft position sensor. Both often fail by becoming heat-sensitive, and they will work again after they cool down. When they fail, the Engine Computer won't turn on the ASD relay and the fuel pump relay, if you have a separate one, so you won't have spark or fuel pressure.
If this turns out to be the case, I just wanted to save you the frustration of looking for the coil problem. Another clue would be if any of the previous coils works when you stick it back in.
Monday, April 18th, 2011 AT 8:20 PM