Go to auto parts store and ask for diagnostics, and a readout, most cases its free, this should tell you the problem.
4.0L 6–Cylinder Engine: Prior to removing spark plug, spray compressed air around spark plug hole and area around spark plug. This will help prevent foreign material from entering combustion chamber.
On the 4.0L engine the coil rail assembly must be removed to gain access to any/all spark plug. The coil is bolted directly to the cylinder head. Remove 4 coil mounting bolts. Carefully pry up coil assembly from spark plugs. Do this by prying alternately at each end of coil until rubber boots have disengaged from all spark plugs. If boots will not release from spark plugs, use a commercially available spark plug boot removal tool. Twist and loosen a few boots from a few spark plugs to help remove coil. After coil has cleared spark plugs, position coil for access to primary electrical connector. Disconnect connector from coil by pushing slide tab outwards to right side of vehicle. After slide tab has been positioned outwards, push in on secondary release lock on side of connector and pull connector from coil. Remove coil from vehicle.
Remove spark plug from cylinder head using a quality socket with a rubber or foam insert.
thanks! that would probably isolate the issue. I was just thinking perhaps the fule filter (not a big deal to fix) or the fuel pump (a bigger deal to fix) or.......something in the computer system (which I understand is a horrible thing to get fixed on Jeeps).