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

Run the 1/4 return off the other end of the rail and take the regulator out of the equation. The 1/4 return will drop the static pressure of the 3/8's 9.5 psi and there will be no chance of vapor lock in the line as it will always be vented back to tank. The calculations for pressure loss are:
where Q=CdAoYρ(1−β4)2ΔP, then ΔP=21ρ(1−β4)(CdAoYQ)2 so its just faster to measure it straight into the return line than do these calculations.
Calculation of Flow through Nozzles and Orifices | Neutrium