You need a new fuel pump I think. You aren't using a booster pump are you?
To be sure you could check fuel pressure at high rpms to see if it is falling. Returnless use a focus SVT pump, return use the trusty walbro 255(GSS 342). I put down 388 on my 2.5 duratec with fuel to spare. Suneil did 402 with the same set up and still had fuel left. Both cars had 42lb injectors.
