did you check to see if your injectors are spraying as they should ,if not its sometimes just as cheap buying reconditioned ones about£40 each( if pencil injectors ) than getting them reconditioned.if an injector is dirty it can cause a bit of flat spot caused by spraying more water than diesel which can damage your pistons. it doesnt sound like you pump unless the lack of power is quite regular.
dave
July 2007