Fuel pressure dropping while driving and under acceleration to zero at idle runs 4 lb electric Blue

Okay here's an update. I took the old regulator apart. Got it out. Drilled it out. It's nothing in it but just a tee to feed both carburetors from the fuel lab regulator. I had access to a brand new fuel pump. I installed a new fuel pump. Tested it. Not as bad as the old pump but still the same thing as the RPMs go up the pressure drops. I'm now going to check into the tank being invented and any other suggestions anybody has. To give you an idea it comes out of a 3/8 sending unit. It goes up a little bit along the frame rail. It comes down to frame rail to where it turns straight into a filter. Then my fuel pump, then another filter and then all the way up to the fuel regulator. The return goes all the way back to the sending unit.