1993 Pontiac Grand Am OIL PRESSURE PROBLEMS

Engine problem
1993 Pontiac Grand Am 4 cyl Front Wheel Drive Manual 140k miles

I have a '93 Grand Am w/ 2.3 SOHC Quad 4. We found a cracked head and replaced it. When we started the car after replacing the head the oil pressure lamp went out for about a minute then came back on. We stopped the engine imediately. We restarted the engine and the lamp went out but imediately came back on. We dropped the pan and pulled the oil pump. We found the pressure regulator on the oil pump leaking slightly and replaced the oil pump. When we restarted the engine the problem is still there. We hear no knocking or ratteling so there must be some oil flow though insufficient to turn the lamp off. This has me baffeled.