Stumbling problem

Checking to see if anyone knows what this might be...

I have a 93 XJ with the HO 4.0L, auto trans. It idles fine and I can rev it up in "park" and it revs fine with no hickups but when I drive it, it drives fine up to about 1500rpm and then it spits, sputters, stumbles, and falls on its nose. It did this once before on a trailride and I limped it back to the trailer and I didn't do a thing to it. I didn't have time to mess with it. The next time I tried to drive it and backed it off the trailer about a month later, it ran fine like nothing ever happened. I drove it as a daily driver for about 3 weeks after that with no problems and then all of a sudden, one morning it started doing it again.

I figure it has to be fuel, air, or spark related.

I pulled all the plug-wires off to see if they were corroded but they all looked fine. Could it be something deeper in the distributor? Maybe a bad coil? O2 sensor? Why would it rev fine until a load is put on it?

Any thoughts?

Thanks much.

check the negative battery cable connections at both ends for looseness/corrosion?

A FUEL PUMP CAN CAUSE A PROBLEM LIKE THAT
PUT A GAUGE ON IT AND PUT THE JEEP IN GEAR AND POWER BRAKE IT
IF THE FUEL PRESSURE DROPS DOWN THATS THE PROBLEM. CHECK THE FILTER, BUT MOST LIKLEY A PUMP. IT WILL REV IN PARK CAUSE THERE IS NO LOAD ON THE ENGINE.
THE PUMP MAY HAVE TO GET WARM BEFORE IT ACTS UP.

HOPE THAT HELPS
JUSTIN

Your catalytic converter may be plugged.

I had a very similar problem. I bought a 93 XJ with 270K on the motor and the guy told me that the tranny was going out b/c it would cut out and sputter along at 1500-2000 rpms. He thought it was in the tranny....so he told me $400 and it was mine. I bought it and drove it 175 miles home and noticed the sputtering he was talking about. It sounds alot like what your encountering too. I ran the problem down to the plug wires. Even though they looked fine, they were worn out on one of the wires. I changed them out with a cheap set of $16 plug wires and threw in new plugs, cap and rotor all for under $40..and it has ran like a top ever since. Not to mention that it has over 300,000 miles on it now!! You may want to check on changing out the wires....it worked for me.