I don't have a computer yet, so I'll throw the coil in this afternoon and see what happens. It's frustrating cause I have to drive it for two hours to see if it's going to foul up! Not friendly on the budget with gas prices the way they are, and the Jeep is not exactly a hybrid!

If you have a computer then you have a sparkbox. Prolly low down on the drivers front fender.. Them things go away like you are describing too. I had one that when it went away I would put a plastic bag of ice on it and she would start up and drive another hundred miles or so before I needed another bag of ice. (I was driving from El Paso to Austin) She made it all the way with the ice bags.
Around here they cost bout $20.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

Could what you're calling the sparkbox be called something else? I've looked on Quadratec, Autozone, and Advance Auto and it's not showing up.

I think they are also called ignition modules. Unless I'm thinking of something different than BJ.

Yes ignition module...
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

Alright BigJim (or anyone else with suggestions), it's still running bad after putting the new coil on. I had it scanned yesterday for codes and the only code that it is showing is that it is running too lean. While we were looking around we noticed a vacuum hose that was in bad shape so I replaced it and that wasn't the problem either. I checked on an ignition module and it's looking like it's going to be $177.00. This was at Advance Auto. I didn't check with AutoZone but I imagine it's going to be roughly the same price. I know the dealer is going to be much more and Quadratec didn't even show one for this model Jeep. I had it scanned at a quick lube shop and while we were standing there watching it run we notice some smoke coming from the dipstick. We pulled the dipstick out and there was some smoke coming from the dipstick tube. Not heavy smoke, but a little bit. Does that shed any light on the subject? Put your thinking cap on! Thanks.

Air should be going INTO the dipstick hole... The reverse is caused by the pcv not not working as it should.
Take the hoses off of the valve cover and clean them internally.. If there is a valve on there get a new one... If not then there is a small restriction in there that needs cleaning to assure full vacuum to the pcv system.
If that fails also then the blowby is becoming excessive..
What I have done in these occasions is to hook both hoses up to a vac source.
Big Jim <img src="/forums/images/graemlins/pfft.gif" alt="" />

Is what we're talking about now, the pcv, possibly be causing it to run as bad as it is after 30 minutes-1 hour of driving? I spoke with someone yesterday about the canister on the firewall that contains a charcoal filter that will sometimes clog up and cause circulation problems. I forget what he called it, but it's on the firewall on the driver's side just under the ignition module and it's about the size of a big can of beans. Is this something of concern for what we're talking about?

I do not know of a cannister giving a running problem.. It should be easy to un plug the vac lines and plug them..
Big JIm <img src="/forums/images/graemlins/pfft.gif" alt="" />

KGH...I don't want to be the bearer of bad news...but when my #4 cylinder went boom...(during disassembly #4 cylinder had broken rings, scored skirt and a nice 'lil chunck out of the piston, not visible with just the head off)...I was blowing smoke out of my dipstick tube.

This was after about 2 hours of driving...I stopped for gas...started her, and she was running pretty rough. So I popped the hood and immediately went to check the oil...this is when I noticed little puffs of smoke out of the dipstick.

Yes, after this my blowby was BAD...so bad, in fact, that the air filter box was soaked in oil, dripping down onto the undercarriage and then my driveway.

THAT'S when I KNEW something was very wrong.

Do a compression check or pull the plug wires on each cylinder and see if there's a difference at each cylinder.

My dead #4 had like 40lbs of pressure and there was no difference in idle when I pulled the wire from that cylinder.