If the pressure regulator went out all together, you would get the full pump pressure at the injectors, maybe 50psi or so and then run really really rich, or you would have gas squirting out all over the regulator if the diaphram blew out. Easy to see if the FPR is working by alternately hooking the vacuum line up to the intake manifold or leave it open to the air and see what the engine idle does. With no vacuum, the engine should load up and run rough until you hit 2500RPM or so. You can test the O2 sensor per the steps in the Factory Service Manual, same with the TPS.