Have you done the simple things yet like a tune up suggested by Jeepete??

C'mon man, you can't expect everyone to answer your questions without taking some action on the suggestions you receive.

Go get yourself a service manual and learn how the basics are done first. You're asking about high dollar upgrades/improvements but don't seem to know how to change the spark plugs/cap/rotor to at least give your Jeep a fighting chance with the engine it has.

Sounds kinda like asking about how to do open heart surgery for a cut on the finger. Ok so I exagerate, but you get the idea.

My God, I wonder how people nowadays would function without the internet. We've become a society totally dependant on others instead of learning for ourselves.

Rant off.