abarry

I posted earlier with a distributor problem on my straight 6 engine. Wrong right off the bat - it seems to be fuel related. I disconnect vacuum from pressure regulator and engine runs just about normal but connect the vacuum and it will bog down and die. If I cover the vacuum port on the tree with the line off it dies. Bought a fuel pressure gauge and so far I can see that it runs around 58 psi without vacuum line and around 48psi with it. No sign of fuel coming through diaphragm of regulator. No black smoke out of exhaust. What should I do next?