77 280z low fuel pressure

Engine stalls when accelerating. Fuel pressure is 25psi and drops to 20 when accelerating. I believe it should be around 36psi. Just installed a new pressure regulator and fuel filter still 25psi. I noticed when I remove the vacuum hose from the regulator the pressure goes to 36psi also there seems to be no vacuum suction on the hose going to the egr valve or the distributor. pleas help.