1990 ford taurus fuel problems
 

Hey, I am working on a 1990 tord taurus with a 3.0L v6. The car will run but stalls out after about running. The amount if time it will run for depends from 2 minutes up to about 10. I have checked the fuel pressure at the engine and it seems to be low, 30 psi. I don't think it is the fuel pump because if i plug the return line the fuel pressure will go up to 45-50 psi immedatley. When the car is running if i speed up the engine and then let it idle down it will just about stall but then come back to a normal idle. When the motor is turning fast it is fine. I think it may be the regulator. With the regulator that was on the car if i unplugged the vacuum hose the pressure would not change. I found a regulator on a scrap van and tried that. With this one on when i unplug the regulator the pressure goes up and when i reconnect it the pressure will drop back down. I don't know that this regulator is good though because it is very old and i don't if the van i took it from was running of not. I don't know if i should just go and buy a new regulator and start with that or maybe there is something else that i am missing. Could you tell me where to go from here? Thanks

Brad