if the engine is 130 bhp tdci you have just a hugh preassure pompe because it's a common rail, I don't think that's a advance problem

if the engine turn well at the idle on his four cylinder I don't think that you have a problem with the injectors

I have the same car and when I'm at low revolution the engine knock a little but it's normal I have the same noise with the Mondeo of my customers

But take some advise to a local diesel specialist

Let we know the diagnostic

Cheers