You need to get some diag tools on it to pin point what's up with it. Swapping out parts on a whim is an expensive way to sort it.
In my experience if it is being a pain to start and slow to build fuel pressure when starting but the HP pump is meeting the pressure demand when flooring it at 3k rpm then it'll be the injectors. Is the head around the injectors dry or are the unions of the high pressure pipes on the injector a bit loose?
In my experience if it is being a pain to start and slow to build fuel pressure when starting but the HP pump is meeting the pressure demand when flooring it at 3k rpm then it'll be the injectors. Is the head around the injectors dry or are the unions of the high pressure pipes on the injector a bit loose?