Oil pressure issue

If you don't see anything obvious I bet the relief valve is stuck wide open in the pump. All it takes is a piece of debris to cause it. Remember the oil pump gets unfiltered oil flowing through it. The filter is on the output side of the pump. All debris in the pan gets ran through the pump.

Your best bet is to disassemble the pump completely. To get the relief valve and spring out you have to yank the small freeze plug out on the side of the pump. It has a cotter pin holding it in place. It's pretty tight in there so most of the time I drill a small hole and screw a sheet metal screw into it and yank it out with pliers. Make sure and notice how the valve comes out and put it back the same after you've cleaned everything good and verified the valve moves freely in the pump bore. Put some light clean oil on things as you assemble it.