1998 Cherokee
 

I have a 4.0 189,000 miles. Oil pressure when warm is 10 pounds. What oil pump do you recommend I will also check main bearings also. Thanks in advance

Appears you double posted. You may be able to delete/edit this one.

Before you do all that throw a mechanical tester on her to get a reading at a very hot idle.
And go from there.
And check the hole the sensor goes in when you remove it to hook up the mechanical tester to make sure it is not all gunked up.