mine did the same thing (96 XJ 4.0 HO). i took the throttle body off and completely apart, soaked it , and put it back together with a very thin layer of high temp permatex. problem solved. when unplugging any sensor , you have to reset the computer. you do this by taking the positive side of the battery cable off and ground it to the body for at least 10 -30 seconds. this will discharge the capacitors in the computer.you can also get carbon built up in the TPS make sure it is clean and working freely...hope this helps
