The problem is that the diagnostic check throws up fault codes, but don't actually tell you what's faulty.

As an example - mine is saying I've got a MAF fault, yet even when I swapped it for a fully functionning MAF from a different Mondeo the fault is still there. The fault codes sometimes narrow down your search, and at other times send you in the completely different direction.

My advice would be to speak to a few local diesel specialists, and see if any of them have a suggestion - The very last thing I would be doing is shelling out getting on for £1500 for a new pump/injectors/rail etc unless I was 100% convinced.