I have a 1994 2 door Cherokee sport XJ with a 4.0L and Manual 5 speed, 270,000 miles. Since I bought her early this year I have replaced the battery, the alternator, the fuel filter, the fuel pump,front brake calipers on both sides, charged the AC, changed the sparkplugs, wires and distributor cap and button. The problem I'm having is starting to occur more and more often. Tye Jeep starts right up with no issues. After it warms up and comes to temperature is where the problems start. It will all of a sudden be non responsive to throttle pedal input. It will stall out and just die like it's not getting fuel, if I push the clutch in and let off the throttle it will die down to idle and maintain there(around 750-1000rpm). If I try to give it any throttle pressure it sputters, spits, cuts out. It seems to have these spells when it's under load as in trying to accelerate or pulling a hill. It's been getting worse and worse as to where I can't even drive her now except around the neighborhood for diagnostic purposes. I've checked the TPS with my multimeter and it test good. I've also removed and thoroughly cleaned the throttle body, fuel rail, and fuel injectors. I don't have the money to just start replacing sensors and am hoping someone can point me in the right direction. Oh, I also removed the catalytic converter last week because a friend said it's looked as if it was getting hot and matched my symptoms. It has only thrown one DTC which was 51. Please help as I need my girl back on the road ASAP.

Bad O2 sensor or damaged wiring to it? That would fit the description of running okay until it warms up and tries to go into closed loop.

I've inspected the wiring as best I could and didn't find anything obvious. Then I unplugged the O2 sensor and started it up, no change at all so I believe that means the sensor is good?