Engine problem with no codes 2.5tdi v6. (BDG)

Hi I am looking for some help diagnosing a engine running problem with a car I have at the moment. I have scanned using vagcom and found it had a faulty throttle body so have since changed for a working one.

The engine starts first turn of the key but is very lumpy. When driving it has no power it can reach 60 but takes a while.

After putting the throttle body in I carried out a full scan and no fault codes have appeared back in the engine section.

Any help would be great

Thanks in advance

Craig

Took for a run and no power at all but once it revs to around 2000rpm it changes engine noise and then thick black smoke. Any ideas people?