Coconino84103

Have now replaced the main and rod bearings and problem still not resolved

Does anyone know what the gap clearance should be for the main and rod bearings using Plastigauge for this 5.3L engine

Oil pressure perfect until a few minutes after engine warms to 210 then drops from 55+ to 20 psi while cruising and then to under 5 psi at idle. I have replaced oil sending unit. No improvement. Then dropped the pan and replaced O-ring, screen and pressure relief valve. No improvement. Then replaced oil pump with high velocity pump and did increase oil pressure from 40 to 55+ psi but then engine warms to 210 and get the same pressure drop. Then went back in and replaced the camshaft thruster plate. No improvement. Last ditch attempt, changed back to conventional oil and put a nice KnN oil filter. No improvement!!! This engine runs so smooth, cannot figure out what’s going on Help!