16,k miles with no modifications or what so ever .i've replaced the oil pump and the cam plate ,all the prongs .assuming that was the problem , put them back together no bueno prior to this i just noticing that the oil gauge was only 5psi.on startup every now and then for about 2-3 munites.
oli and oil filter was new from HD. is there any checkvalve anywhere in this oiling system ?
and also check the crank runout is just .03 thanks

 

There's a spring loaded oil pressure relief valve in the cam plate.

 

Could be a bad sending unit, replace that and see it that helps 1st.