I'm not sure about the oil if you're sure that is what you found, may be blow by which sounds common in Jeeps. Lots of different things people have done to fix this but maybe someone will be by with a better answer. The black residue is carbon build up. Try cleaning out the throttle body with some intake cleaner. You may want to do your spark plugs as well but do the cleaner first.
2006 SE 2.4L(4 angry squirrels under the hood)
3.25" RC lift with quick discos, 31X10.50R15 Firestone Destination MT's mounted on 15X8 Black D Windowed Wheels with 4" BS, Magna Flow Exhaust, K&N Air Filter, Bushwacker Rocker and Corner Guards.
RMGO "It's a Right, not a Privilege!"