hey guys new to the forum. got a problem child jeep.....
to begin with, originally had an engine replaced due to having a cracked piston. and then came the problems (although not related to the actual engine as it was the block and head which were replaced). when the engine was replace so were distibutor cap and rotor button, leads,plugs, water pump, head gasket, and battery. Ran fine for a while then noticed a roughness in idle and general running and occasinally a random bucking like it was starving of fuel. removed dizzy cap and found exessive movement in the shaft and a the tip of rotor button to have worn loose..... ok then replaced distibutor. Noticable difference in drivabiltiy, much smoother although still had the random bucking on the highway.Connected up a fuel gauge and although noticed no difference in pressure thought it was worth replacing fuel pump as it is a common fault with the old girls and replaced intank regulator as there was visible gunk caught up inside it. So after all this she still does the same thing, drives along fine then will randomly buck then continue on the way. It seems like a fuel problem but i dont know im running out of ideas. i have scoped the map and crank angle sensors and unable to seen anything wrong, the ecu has been sent and tested.

ANY HELP APPRECIATED ........GOING CRAZY HERE lol

 

Bad O2 sensors?

 

Don't just keep throwing parts at it what exactly is it doing now?

 

I'd put lunch money on a failing TPS or CPS if it's doing it hot or cold. O2 sensor, as jj mentioned can also do that, particularly if the stumble is around the transition to closed loop, but can happen at other times too.
Unplug the O2 sensor and see if the problem goes away. You'll get a CEL, just reset it later. o2 sensor connector is on the driver's side of the block, down real low. Follow the sensor wires back from the downpipe and you'll see it. Make sure they aren't damaged while you're down there.

The TPS- check it with a voltmeter- center wire- key on, engine off. Should be less than 1V with the throttle closed, smoothly increasing to just under 5V as you slowly operate the throttle by hand. Watch for dropouts or stumbles as the reading increases.

The CPS can be tested- sort of- by checking pins B and C (center and right pins) as looking into the connector. Should be in the order of several megohms resistance- basically an open circuit. It's better tested with an oscilloscope watching the square wave output, but that also presumes it'll act up while you're watching.

Thing is, you have an intermittent failure and static testing usually won't uncover that sort of failure unless you really luck out and it acts up while you are testing. "it's fine when I take it to the shop" lol. Fun, fun.

My '96 started pulling a similar act on Friday, it'd stumble as though the key were momentarily shut off, nearly stall, then recover and run fine for some period of time after which it'd repeat the same stumble and recovery.
I watched the live data on my scanner and couldn't see a thing wrong. Static test of the CPS, TPS, Coil, no faults. Cleaned the grounds, PCM connectors, check the cap, rotor- nada. Still did it.
I still had the OEM CPS in there, so on a calculated guess I changed it and the TPS which also dated to 1996. Intermittent stumble gone, so far. They don't always do a hard failure.
That may or may not be your problem, but sometimes with intermittents the only real, workable test is substitution.