After the engine is warmed up , traveling in 5th gear , at a constant speed, the oil pressure guage jumps around a lot from 55 lbs to 30 to 55 to 0 to 40 to 55 for a while, then starts jumping again.
Could this be a pressure switch sensor problem rather than a actual pressure loss, or something else?

Id think it would just be a bad switch.
My brothers jeep did that and i think he just replaced the switch.
If there were a problem with the pump it wouldnt be intermitant.