Start by replacing the fuel filter ($35 for a genuine item), then borrow/buy a fuel pressure gauge and hook it up to the fuel pressure regulator (if it isn't working replace it), replace fuel pump with a Walbro GSS342 (cheaper of the 2) or Bosch 040 intake pump. Just make sure to get either pumps from a forum sponsor, don't get suckered into buying a chinese copy off ebay etc.
Just start with the cheaper things, then if they dont solve them, replace the fuel pump as last resort.