Fuel pressure problem..I'm at a loss.

I fought a similar issue for a year. I feel your pain. I found the flare on the vent tube closed the tube down to less than 1/16” among other things. Finally put a holly red pump at the tank and a big mechanical up front. The red also makes starting it nice after the fuel evaporates out of the carb when the car sits. Rock steady 5 lbs.