Yeah, need more info regarding fuel delivery. Don't forget that the fuel must mix with air before going into the combustion chamber. Therefore, if there's a bad leak or not enough air getting in, it could stutter.
When you replaced your spark plugs, was one (or more) covered with oil or grimey? They should be a burnt white/charcoal color. If it's got oil on it, then you have blow-by, where the oil is getting past the piston and can cause misfires.
Check your oxygen sensor, or have it checked. But i would have to bet on some type of air leak/vacuum leak.
But the bottom line is, if you paid $ for repair and it's not fixed, make them do it for free. Get pissed and embarass them in front of other customers... it will make them nicer... or else sadistic, and booby trap your jeep. Good luck... let us know what you find.
C