CHECK VACUME LINES!!! have been having intermittent probs. with my 97 grand cherokee since i bought it last year with idleing, sometime idled @ 2000 rpm, sometimes normal, replaced IAC valve, had same prob., occasional stalling, but starts right back up, sometimes hard to start, somtime starts rite up, DRIVING ME NUTS!! Decided to reseat PCM connections, dam thing wouldn't start at all unless i pumped the hell out of the gas pedal & had to keep pumping till it decided to smooth out and run, was going to buy PCM as a last resort when i noticed the hard plastic vacume line going to the cruise control motor was broken. Spliced in with rubber vacume line & tie wraps-PROBLEM SOLVED!!!!! On closer inspection i could see where the line at some time or other had gotten a small melted spot(cig burn or whatever) & might have had a hairline crack that was growing & when i was messing with the PCM i obviously bumped it & finished it off. i guess the PCM was keepig it going the best it could!!!