Start simple, make sure the computer has the correct parameters learned. Disconnect the battery to reset the computer, then when you go to start the Jeep, turn the key to on (not start) for three seconds to prime fuel pressure, then turn it over to start. If you have erratic idle after that, there's a malfunctioning sensor or you may have a vacuum leak somewhere. If possible, get a scanner on it with live engine data to look for abnormal fluctuations in sensors. Throttle position sensor should read about 15-17% at closed throttle; if it fluctuates even slightly when you're not moving the gas pedal, it's a bad TPS. Same goes if there are any dead/irregular spots when slowly moving the pedal from closed to WOT.
This is usually caused by a bad TPS or IAC, but a junkyard/reman PCM could easily be the culprit.
2003 WJ in Jeep Green Metallic, 4.0/242/4.10's. 4" Teraflex springs w/ RE monotube shocks and IRO short arms, cheap intake w/ amsoil filter, 2.5" hi flow cat and back exhaust, lots of lights and other misc crap.
Check out my build thread here:
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