Low oil pressure stop engine with 30lbs of pressure

[DrPhixschitt]

2016 Pete 348 with a Paccar PX-9/Cummins 8.9 ISL. Newly rebuilt engine, new sensor. At start, oil pressure reads 60-70. After reaching 180 degrees, pressure drops to 10-15 at idle, the light starts blinking on the gauge, stop engine on dash, and alarm goes off. Touch the throttle and it stops until about 30 lbs, then it comes back on. I’ve ran all the wires, took the pan off, all was good. So now I’m thinking wrong oil, or the pump behind the front cover wasn’t shimmed and leaking. Getting good oil to the valve cover. If anyone has an idea it would be greatly appreciated.