[unclebubbles]

You may have sludge and debris floating around in the pan thats partially clogging the pickup screen at times.(sludge, old pieces of gasket, peices of valve stem seals...ect). Or it could be a mechanical problem. the best way to tell, is to install a real oil pressure gauge, then youll know exactly what the oil pressures doing. The "sending unit" thats on it, is nothing more than a switch. Anything above about 4# of pressure , gives a half scale reading, much less, and the gauge reads 0.Good luck.
Later
Ed