I have a 91 cherokee sport has 243k on it needs work and i need your input 1st its knocking at start up and at about 2000-2500 rpms oil pressure is at 20lbs .. i was thinking rod bearings clean pick up tube and new oil pump... what you guys think??? 2nd it just started missing at low rpms or going up hill? i have noticed i can hear the fuel pump after it warms up plugs and stuff are new any ideas

 

Run a compression test on all cylinders before deciding what to do. You may be on the tail end of this engines lifespan.

Compression spec for the Jeep 4.0 is 120-150, with no more than a 30 psi variation between cylinders.