Fuel pressure fluxuation problems

[bermblaster41]

Looking for some help from the experts. I have a 408 windsor with fuel pressure fluxuations. I have a holley mechanical fuel pump 130 gph feeding a quick fuel double pumper. Between fuel pump and carb I have a inline filter and holley pressure regulator. All lines are steel braided. Fuel line from tank runs along inside driverside frame to the pump. From pump back along frame up to firewall to firewall mounted pressure regulator then to carb. When the enginge is cold fuel pressure is at 6 psi. When the engine warms up pressure drops to approx 2psi, sometimes even lower. I have the holley press regulator with one inlet and 2 outlets. One outlet goes to the carb and other to pressure guage. I have change pres. regulator and guage with the same results. I suspect vapor lock. I have know idea how to fix this problem. I am using a victor jr intake without a spacer due to hood clearance. I also have wierd plug readings. The front plugs #1 #5 are black . #2 #6 are blackish brown. #3#7 are brown and #4#8 are gray. I am guessing another symtom of varpor lock/ fuel starvation. Any help would be greatly appreciated. Bermblaster