Where are you measuring the fuel pressure from? The filter? If so, something could be blocking the flow into the fuel rail causing the flow to skyrocket in the line up to the rail.
Check the little hat looking thing on the side of the fuel rail opposite the regulator. There is a little screw with an o-ring on it. On my setup, whoever had my motor before put too long of a screw in it. This didn't allow the little spring loaded valve inside to open all the way, restricting fuel flow.
If thats not it, there could be a kink somewhere in the return line. One way to check that is to vent the return line into a gas can, bypassing the entire return system. If the pressure is correct, then you have a problem in the return line.
