Alright, let me see if I can get this right this time.... I can't remember if you changed the fuel filter and fuel pressure regulator, or not, but I would actually start there first. Both of them are inexpensive, easy to replace, parts so I would go that route before dropping the gas tank to get to the fuel pump.

If you have replaced those two things then the fuel pump would be the next in line (unless the fuel lines themselves are clogged).