Doesn't accelerate well

I have a 98 4.0 / 5-speed. Since it was new I notice that when going up through the gears at revs between 1500 and 2500 ( my rev range) it just doesn't pull smooth. At 1/3 to 3/4 peddle, up hill or on the level makes no difference. Its like a lean surge or something. I can't quite explain how it works but its like your pumping the gas peddle a little bit. Like I say it has done it since new and has had several plug changes and is well cared for. Is there anyone that has a 5-speed and the same problems.

If the Jeep is "surging", I would look towards the TPS(throttle Positio Sensor), how many miles are on this XJ.Mine has 86,000 and never changed the fuel pump/filter, but you might want to get a pressure check done, to see if that might be the problem.

Its has 109000 kms ( 65000 miles) its the funniest thing. works great except for that .