Very VERY intermittent bucking during accel problem. I am at a loss! Help!

I have been dealing with this "bucking" during light accel for quite some time now. It is very intermittent and I can sometimes go weeks without having it happen even once. Today it seemed to have done it probably 20+ times at random. It never has happened during a hard accel or WOT but only seems to do it at about 25% or less throttle. It feels exactly like you take your foot completely off of the gas and then immediately slam it back on. It never does it over and over and over at the same time but only once and then it goes back to normal for sometimes a few minutes / miles or weeks before it does it again. I have replaced cap / rotor / plugs / wires / TPS / fuel filter / within the last 100 miles. Both o2 sensors check out fine. I pulled the throttle body completely apart today and cleaned and checked everything there and all seems ok. The exhaust has been replaced within the last year and this problem has been going on for the past few so I am really at my witts end with it. It idles perfectly smooth, starts right up every time, and no codes are on the ECU so I have no idea where to go from here. It's a 5 speed 96 XJ with a motor out of a 98 and only has about 60k on the odo. The motor was done about 8 years ago so I can rule out install issues as this has been going on for the past few years now. Where do I go from here? Even when I have come across a Jeep tech I can never replicate the damn problem no matter how many miles they drive around with me. Any ideas on suggestions on what I can check next? Please help as I am at a loss here!

Are you sure you don't have a Ford? LOL...those are notorious for intermitents.Anyways try running some Techron injection cleaner in there if you have not all ready.Also more than likely the ignition coil could be shorting out.It would act up more when it gets hot and or in high humidity/rain.I would check the primary and secondary winding Ohms resistance when hot.Quick check on crank sensor.When it acts up pull over shut it off and unplug the crank sensor and plug it back in...see if it goes away.

I had very similar problems with my 92 w/ 230K. The bucking progressively got worse as time went on but mine would clear up when engine came up to temp. My problems were the 2 pcv intakes under the valve cover. They were completely clogged giving the computer a false reading and fattening the motor. As the motor come up to temp the gunk would loosen up at let air pass. Cleaned them and now it runs like a top. Pull the PCV elbow off and look down in. If it looks like there's a bunch gunk in there I would pull cover and check. Hope this helps

Check that the CPS cable hasn't gotten burned on the exhaust.

Had a somewhat similar problem on my 1995 YJ years ago, was due to weak valve springs. A swap to fresh springs solved the problem.

Thanks for the replies I will have to check all of them. I didn't mess with it anymore last night and today I drove it around for almost 3 hours and it didn't happen once. This damn Jeep is going to drive me nutty!

I would check your injector spray patterns. Might be clogged? I know there is a screen inside the injector, but I'm not sure on how to check it.

sounds like CPS or TPS -sensors or wiring.

I had an intermittent bucking problem in a completely different vehicle ('90 Trans Am) that took me over a year to finally pin down. Wound up being one injector which would intermittently short out, and it seems that when it did it would bring down the rest of the injectors. I have no idea if the injection system on an XJ would be prone to the same problem.