having oil pressure issues

[drkwaterdiver]

Hello , I'm going crazy here and hoped somebody here could help . My motor is a 557 based on a fully race prepped 460 block and has about 4 hours on it till the pressure started going crazy . It had 60 psi at idle now its bouncing from 15 to 25 and tops out at 30 . The motor isn't ticking , knocking or making any unusual noises at all , changed the oil 2 times I'm running brad penn sae 40 , cut the filter open and no glitter or flakes also dropped the pan and checked , new oil pump and gaskets , new gauge hooked directly to the block . I even pulled a few rod and main caps off and the bearings look great . I really don't want to pull the motor and go through the motor again so any ideas would be great .
Thanks

 

[Bronco638]

Any chance you're sucking air where the oil pick-up tube goes into the pump/block? I had that happen on a Fiesta many moon ago.