fuel pump failing?

Change the fuel filter. If that doesn't fix it check the fuel pressure. If the pressure checks low, find and crimp the rubber return fuel line if it has one. (You could have a returnless fuel system which will only have one line going to the engine.) If the pressure rises, it's the fuel pressure regulator. If not, it's the pump. Dont even think of putting in a junkyard pump....that's crazy anyone would even suggest it.

Your pump may not be pushing enough pressure injection pumps average 60 to 65 psi and if it falls below that your injectors cannot fire enough gas in the .003 seconds they are open a shop can check your pressure and a junkyard pump should work or you can spend a little more and get a new one. typical problem if your car sat for a long time without running or you have debris in your tank. I don't know if that would be covered by a warranty at this time but i have had to replace mine and it solved a simmilar problem.

I would start by replacing the fuel fliter assuming you havent done this yet, a cheap part, and is regular maintenabce any way. If it is starting to get dirty/ clogged this would cause the symptoms you are describing.