Try disconnecting the return line right there at the regulator(have a jar handy to catch fuel in). It sounds like you were in the right spot, at the end of the fuel rail (firewall side)where a fuel hose exits and has a vacuum line connected. There has to be fuel coming out with the engine running. If not, i'd say you may have a blocked regulator. High vacuum means lower fuel pressure, low vacuum means higher fuel pressure. If you have a blockage, it will be high. I think normal fuel pressure is around the forties. If you have a fuel pressure gauge you can tap it into the port that feeds the cold start injector.
I don't know the name of the distributor, the parts department got it for me, I know they go through a couple different ones, whoever has it at the time.
