Carter fuel pump bad out of box?

Breaking in my new engine on a proven good fuel tank (running my slant 6 perfectly just days before) I experienced a fuel starvation issue after going a mile down the road several times, with no fuel squirt when looking down the carb. I let it sit for 5 minutes fires back up, down the road we go and it does it again. I put a fuel pressure gauge on and I get a little over 5 psi at idle. If I hold 2500 RPM, pressure bounces and then drops to to near zero in about a minute. This is on a cold engine with the hood open, so I feel that vapor lock is not a factor. Pump is a brand new Carter Muscle Car for small block mopar PN6866. Edelbrock 1405, Edelbrock dual plane airgap, Magnum 318 .030 over. New Edelbrock metal can style fuel filter kit. 5/16 in and out of pump to 3/8 rubber to filter to gauge to carb. Using Headers in a 67 Dart. Runs great otherwise! Anyone had these pumps be bad out of the box?