No oil pressure with PCV hooked up

[vgames33]

Engine is a 2002 Chevy 5.3 Vortec from an Avalanche, currently installed in an 88 300zx. Roughly 110k miles on the engine, about 500 on the swap.

I drove the car for about 300 miles with the PCV system open and the ports on the intake capped off. Bought some hose and hooked in the PCV, and the next day I start having oil pressure issues at hot idle, especially right after exiting the highway. I unhooked the PCV lines from the intake and pressure came right back to about 20 at idle.

The oil cap was nearly impossible to remove with the engine idling and there was a very large rush of air when I finally got it out, as if the valve cover was under a very heavy vacuum. Is this a symptom of a faulty PCV valve or something else?

[vgames33]

Nevermind. I had both valve covers hooked to intake vacuum. I put the passenger side breather to atmosphere and everything seems fine now.