I have a 99 suburban 350 5.7 vortec the engine was just rebuilt and it has 3-5 lbs of oil pressure and drops to zero at ide (mecanical gauge) we replaced the oil pump last night and still has the same problem i was wondering if anybody have and ideas of what to check. could the oil filter adapter with the cooler lines have anything to do with it? is there a relief vale in it? thanks Fustrated

Change the sensor. it appears to be a known issue.

https://www.autopartsrepairs.com/causes-low-drop-oil-pressure-dodge-ram-trucks/

Durango

https://dodgeforum.com/forum/1st-gen-durango/276936-oil-pressure-gauge-drops-and-rises.html

https://www.google.com/search?q=%2799+Dodge+Ram+1500+5.2L+Intermittent+sudden+drop+of+oil+pressure

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I have to ask if you are sure the oil pressure drops first, or the engine stops first. The engine would stop if the oil pressure dropped below 5psi but only because the fuel pump would shut off. And it should start back up if that were the reason.
If something such as a relay or the ignition module is getting hot and killing the engine, it might have to cool down before it restarts. And the engine would stop then the oil pressure would drop to zero.

With an oil pressure gauge:
Remove the oil sender unit and install an oil pressure gauge at the cold engine and let the engine warming up. And record oil pressure data.
You will see if the oil pressure match your problems if so then there is an internal leak or bad oil pump or old engine oil.

Hope it helps.

The 4.3 engine should have 20 to 30 psi at idle cold and around 50 to 60 psi running down the road. Has this engine had regular oil changes? If not the problem could be sludge build up. The oil pressure sending unit could be the problem. If in question about the sending unit install a mechanical gauge and watch the pressure.

The camshaft bearings should always be aligned so that the oil holes in the camshaft bearings are aligned with the oil passages in the engine block regardless of their position.

at a bare minimum of 15 psi

dont accelerate in neutral

on general motors engines all the way down to 15lbs of oil pressure is acceptable i prefer 30 but if the 40 you have down is the lbs of pressure your in good shape brand new engines generally only have about 45lbs of pressure

check the oil descending unit or ur oil pump might b clogged up with soot, just some advice hope it works

CHECK THE OIL PUMP SUMP TUBE O-RING. THEY COLLAPSE CAUSING THE OIL PUMP TO PULL AIR INSTEAD OF OIL. TO VERIFY OVER FILL ENGINE OIL AND CHECK ENGINE OIL PRESSURE. THIS IS A COMMON PROBLEM ON ALL NEWER GM V-8 ENGINES : 4.8 5.3 5.7 6.0