Black smoke is over fueling, you normally get this type of thing when donkeys fit the plug in boxes that trick the ECU instead of a professional remap.
EGR valve is normally puts on the engine warning light it recirculates exhaust gasses back into the combustion chamber to cool combustion and increase effeciency (MPG). If there is a problem and it goes ignored then uncooled gasses pass through the turbo causing it to overheat and wreck the turbo bearings.
If the light hasn't come on then I would assume it's a mechanical issue and not sensor related.
I watched a program not so long ago about second hand cars and they had a Ford Mondeo ST on it, it was a 2.0 TDCi and when they were going on about faults they mentioned that in some cases the injectors went at 60k. The other fault was all the rear suspension bushes fail at 40k.
I think you are going to have to pay a garage the stupid £30 for running a diagnostic check.
Check out this link but it doesn't sound like a cheap fix.
http://uk.answers.yahoo.com/question...3135828AAvL0wh