Dart falls on it's face.

My motor seems like it is running out of fuel at high rpms sometimes. It can pull hard to 6K in first and second sometimes, but other times it seems like it is running out of fuel. It acts like someone turns off the key at around 5 K for a couple of seconds then it cuts up then runs normal.

Here is some specs on the motor. 318 9.0-1, 904, magnum heads, XE 256 cam, hookers, 3" exhaust, holley 4160 600 cfm, fuel cell with sump, holley red pump.

I have a fuel pressure gauge before the carb and I am getting a constant 5 1/2 psi and flows like a river when disconnected. I am running a high capacity fuel filter before the pump and another filter before the carb. I have checked both filters and they are clean. I am feeding my first filter from the fuel cell with 8an and also 8an to the pump, then I am going to 6an then to the factory fuel line. Is the factory fuel line too small to power my little 318? Should I step up to all 3/8"?