Hi Mark Just had exactly the same experience with a 1400 TDCI, came in with compression blowby on injector copper washers, No 2 siezed in head and the plastic seal at top of the injector had melted, was running fine just blowing past injector, removed injectors,( No`s 2 and 3 with difficulty) cleaned up refitted with new washers. leakoff pipes and manifold seals started and idled fine, sweet as a nut just absolutely no power, would stall just getting out of the workshop, rechecked everything as you have, checked live data ok,ended up with new set of injectors and all is well (or if you are James Dillon happy days!)
I`ve changed hundreds of injectors in my time, (common rail included) never had a problem like this, seems to be a common problem on these engines, probably a good idea to advise customer of the possible need for a new set of injectors when taking this job on again, (or running a mile from it!)
Just hoping this might help someone.
Best regards Roger.