Had a car in the shop the other day with the same symptoms and the sock on the fuel pump had so much stuff on it (from a dirty tank) that the pump could not pump any fuel inside of it. We cleaned the tank and fixed the dirty sock and it was back to good again. Definately sounds like it is fuel related. Have you just installed the pump? Check to make sure it is sitting down in the tank properly. I have seen them installed where they were out of the fuel at a half tank of gas, and so the guy thinks he has plenty of fuel but the pump cant get any of it.