Originally Posted by xjdantheman
fuel pressure regulator, pull the vacuum line and see if its wet and smells like gas if so then replace it...
If it was an 1995 or older Jeep, this might be true. Not so much with an OBD-II Jeep.
Why were all these parts replaced, routine maintenance, or some issues you were trying to shotgun cure ?
Poor running, and severely decreased gas mpg's often points to O2 sensor issues or exhaust manifold issues. Has you checked/tested the O2 sensor fuses and wires ? Have you tested the O2 sensors ? Are they BOSCH O2 sensors ? Have you inspected for cracks in the exhaust manifold ? Have you hooked up an OBD-II trouble codes reader and checked the live data ?