1991 Buick Park Avenue oil pressure

This vehicle buick park ave 3.8 was one owner, bought it 6 months ago. Ran fine, no problems. Timing cover started to leak anitifreeze and had a camshaft code. Found timing cover leaking, magnent gone off of cam gear.
replaced camshaft sensor, crank sensor, timing gears and chain, magnent. Also intake gasket, valve cover gaskets, plugs wires, pcv. Crankshaft seal.
drove it 10 miles and oil pressure started to drop, gauge and light. Engine started to knock a little. Towed it back. Found crank shaft seal leaking oil, replaced again, recheck work. Only a half qt low on oil. Started car, engine cold great oil pressure 50-60 psi, once warmed up oil pressure dropped and had slight engine noise. Pulled oil pan, check screen at oil pump, had some small debris on it cleaned and reassembled. Also checked main bearing- looked ok. New oil and filter again.
still has same problem cold it runs great
good oil pressure, warm it drops at red line, light blinks, slight engine noise. Do I have a problem with the pump? Problem with camshaft bearings?