Bizarre oil pressure woes

[fxportapot]

2001 tahoe 5.3, has strange oil pressure, so lastnight after about 40 minutes of hwy speeds the oil pressure slowly moved from 40@70mph down to 20 once it goes down it no longer would come up even with rpm changes or stoping going again, the heads started to make chatter, I pulled over and shut it down, checked the oil and its at max, started it back up and oil pressure came back up, drove to my destination about another 10miles no other problems. On the way home same exact thing after about 40 minutes the gauge dropped and would no longer come up, the heads start to chatter, I pull over shut it down for 1 minute, start it back up and drive home no problem.
It has about 210k and about 5k on new heads/gasket, leaks no oil, no coolant, just had the oil changed at the dealer about 1k ago. Also no indicator lights came on, I just heard chatter and pulled the heck over.
Could it be as simple as a clogged oil filter?
I'm not leaning towards the pump cause I'd think it'd go out and id have indicator lights....(maybe wishful thinking)

 

[07Burb]

Sounds like it could be a simple sensor issues, something is clogged or could as serious as a bad lifter

 

[fxportapot]

I doubt it's a sensor since it started making valve train noise. I'm gonna pull the pan and clean the pick up tube and see what else I see, I'll also swap the oil filter, start with the simpler things I suppose

 

[BRUTUS_T_HOG]

Probably clogged pickup or cracked o-ring on the pickup sucking air

 

[fxportapot]

Update: so I checked the oil again and it was actually over filled, thanks dealer, I swapped the filter for a k&n larger one instead of the acdelco I think it was a 46e maybe.... Took it for a drive and it stayed at a steady 38 at idle and maybe 50@50mph, a longer drive will tell, I'm going to dissect this filter it looked f'd up inside like part of it was crushed. I added no oil after swapping filters and it was still right at max.
These engines do have a built in the block oil filter bypass correct?