You might want to move this to the 2nd Gen sub-forum.
Likely culprits to check:
1) Check for codes ...for example ..a TPS code or Tranny governor?
2) TPS (throttle pos sensor) ..can cause shifting issues
3) Connectors on tranny/xfer case, and or PCM (wiggle them, check for corrosion and power to the shift solenoid. If no power go to PCM)
4) Speed sensor
5) Leaks in EGR pipes, or cracked hose ends (or bad PCV). You wouldn't think it would affect operation, but I've seen it do so.
6) Is the tranny shifting properly? The governor pressure solenoid (inside the oil pan) commonly fail on those trannys and cause shifting problems. Do a google search ..and there's some youtube videos on this.
I had a '03 V8 Jeep GC with tranny shifting issues (probably same tranny). Code indicated shift solenoid (fairly common). I had replaced TPS (no difference). Dealer replaced trans shift solenoid ($300) and all was good. I was super-busy at work ..so it was a reasonably priced, quick fix.
Good luck!
