It could be something else causing the power loss. Which a fault code reader may pick up on.

Try unplugging the little black hose to the turbo (the one that gets in the way when you remove the engine cover) and see if the car feels any different (it should feel flat as fuck with it removed) if it's no different then it's turbo vac problem. Also have a really good look for leaks from the boost and especially the other vac hoses.

I don't think it's a timing issue as you'd probably have problems with it cutting out, starting badly etc. Knowing that car it's probably something minor which is going to be a right arse to track down.

Maybe consider finding a diesel specialist before you take it into a Ford main stealer.