Hope someone may just have a suggestion to my problem.

car… 2008 Ford Focus 1.6 TDCI

problem… massive loss of power, car won’t rev above 2000 (that’s free reving) and as revs are approaching this limit becomes extremely smokey

when occurred… was running fine, parked up for 4 hours, started it up and been like it since.

additional info, Engine sounds fine no knocks and seems smooth, pretty convinced nothing mechanically wrong with engine.

This is a replacement engine as of about 6 months and I still have many parts off old engine so have already tried replacing a number of parts including MAF sensor, Map sensor, EGR unit, checked the turbo, seemed free and have observed it spinning whilst engine idling.

have had it on two diagnostics including FORScan was some codes initially but no codes returning now so also seems unlikely an electrical/sensor issue?

my best guess would be something on the fuel/air side of things? The fuel filter isn’t all that old and the consistency of the revs makes me believe it’s not this. I have checked intercooler and pipes best I can and seems okay also can’t hear any air leaks.

At a bit of a loss as to what else to check, any suggestions much appreciated, thank you.

Certainly sounds like the mixture is far too rich. Maybe time to consult a diesel specialist, assuming the air filter or intake isn't blocked or clogged up (I once had a rag sucked into the air filter intake many moons ago...)?

Sounds like limp mode masking another fault. 

Are you getting an engine malfunction warning?  What were the initial codes?  Underboost?  Glowplugs?

Is the turbo vane rod moving at all?

2008 Focus, try whacking the dash above the instrument cluster. Usually generates ‘U’ codes if it’s the dry joint issue. Probably not the issue but good to rule it out.