TDDI isnt common rail and as such doesnt have electronic injectors but always use good quality fuel filters like gen Ford or Delphi as pumps are temperamental.
TDDi in general dont suffer as bad with the DMF/clutch problems as many are only 90hp or 115hp versions so less stress on these compnents.
Lack of power could be many things but dirty/clogged EGR valves are a common problem. Theyre very easy to get to and clean out though and a flat blade screwdriver and 8mm socket is all you'll need for removal..