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

The 512 in my Challenger has a issue with losing all fuel pressure. Let me start by stating that everything in the car is new...pump,lines all of it.

This happens about an 1/8 mile after I stand on the gas, runs fine while throttle is down and then, about 1/8 mile down the road after I let off it starts bucking and, eventually will die with ZERO fuel pressure. Let it sit for 5 minutes and its good to go until I stand on it again.

I can drive this car for hours and have no problems at all until I get down on it.

I also want to include that I had this kind of issue last year but, when it was chugging before it would die it was actually blowing gas out of the vent in the front bowl, I replaced the float and it does not do that anymore. I also put a new Carter mechanical pump on this spring and right out of the box it was pushing 9.5 lbs of fuel pressure so, I put a Holley regulator on it and, dialed it down to around 5.5 lbs. I had also found some debris in the regulator one when this happened and, found that the sock on the sending unit had came off in the tank so, I also replaced the sock and, while the tank was out we blew air through the fuel lines to get any debris out of the lines, really thought that was going to solve it...it did not!!!

I have noticed that fuel pressure seams to drop after the engine has warmed up. When I first start the engine it will have 5.5 to 6 psi but after its warm I have seen it all the way down to around 4 psi. So at 4 psi if I drive it responsibly I figure its enough psi to run it but not enough to feed the 850 double pumper with 50cc accelorator pumps? Why the big drop in fuel pressure once it warms up? I'm at a loss...