Fuel injecters

Go by one of the parts stores and pick up a fuel pressure tester. It will attach to the test fitting on the fuel rail( looks like a bicycle tire fitting). If your regulator is good when you disconnect the vacuum fitting from the regulator your fuel pressure will increase. Next shut off the car with the tester still attached and see if the pressure holds for a short time and slowly starts to drop. A sudden drop to zero or a fast drop would indicate that the regulator is bad or failing.