88 f-150 302 5.0 V8 5spd manual.


start it up pressure is fine, drive it around and it gets warm (normal temp) oil pressure drops. well not while driving unless its a 35mph zone and im in 4th, but if its warm and im at a stop light, oil pressure drops to 0 and engine idol drops reallllllllly low...what is causing this?

me and a buddy figured maybe the rods and main bearings?
cam?
burnt valves?
collapsed lifters?
clogged oil screen?
bad oil pump?