Fuel pressure problems

What brand/ model of regulator is this?

Most mechanical pumps I'm aware of should not NEED a regulator

This sounds like vapor lock. I'm a HUGE fan of "vapor return" systems.

Your car is new enough that unless you've removed it, you probably have a return line for the carbon canister system. If you can go back to an open vented system, free up the cannister tube, you could use it for a vapor return.

Wix makes two inline metal filters with a return port, one 3/8", the other 5/16

First one of these systems I ever saw was factory on my old 70 RR, 440 sixpack. IT WORKED!!