97 Tahoe Fading oil pressure

Please help…

97 tahoe 145000 miles 5.7 4wd

cold start truck and get about 45 lbs.

As it warms it will gradually fade to NOTHING at idle in gear.

So far rebuilt the bottom end,

Cut crank -new main and rod bearings -High volume oil pump new pickup and screen. Reads the same with a mechanical gauge.! week prior to this problem i had changed the intake manifold gasket…any connection???

Im hoping you dont tell me cam bearings

Thanks for the help…

Have you considered different oil? Have you checked the pressure regulator.

What is your pressure reading at say 2000 rpms?