84 max, no oil pressure at idle

I am new to the forum. Just bought an 84 max wagon for $50 from a neighbor because he couldn'd find an electrical short that was occasionally keeping the car from starting for anywhere from 20 min to 2 days. Anyway, it was sitting for about a year and a half before I got it. There were a couple loose wires from the starter and the positive terminal on the battery. I replaced all of the normal tune-up stuff and checked the timing, all good, runs strong and smooth. Then I noticed the oil pressure at 0. Once I get it up around 2k rpm the pressure slowly climbs and holds, then drops out again when I let it idle. This happens much less when the engine is cold. I pulled the oil pump and checked it. There is a little scoring, but not bad for an engine with 160k on it. I couldn't find in the manual any type of pressure regulator that might be bad, but I can't find my shoes if they aren't on my feet. Does anyone have any suggestions?

Thanks for any help in advance

So I have put in a new oil pump and pressure sensor. The valves have started tapping as you would expect for an engine getting no oil pressure. The idea I have gotten from anyone is that the bearings may be worn and not creating enough backpressure to get the oil to the cam rail. I am a little dubious about that, but nothing else has seemed to work. I have flushed the motor a few times now in the hopes that it was just a clogged strainer or ports, no luck. Any ideas out there? I am about to have to take it in to the shop and probably pay out the nose. I'll try just about anything.

Thanks
James

I kept my 83 GMC s15 PU running for an extra 6 years by adding one or two cans of STP with each oil change. pressure went from about 20 lbs to 60.

It may save you 2000.00 on a rebuild