I had a similar problem, turned out the tubing from the 'new' tank was FULL of crud, new line fixed it. I also have gotten an inline pressure gauge so I can see what is really going on.
I also quit using the fuel pressure regulators that I used to rely on, the new ones are junk, can stop the fuel flow at the worst possible time.
If all else fails go through the tune up proceedure per the shop manual, just may stumble onto the problem.
