You'd need something like IDS, the proper Ford diagnostic tool to monitor the fuel pressure on datalogger mate, which unfortunately would mean booking it in somewhere. As for the injectors, you can do what's called a leak off test which would give a good indication as to how each injector is working, but again you'd need to book it in somwhere for that. Sounds a ball ache, but probably cheaper in the long run, rather than guessing at things and spending money for no reason if that makes sense?

Karl