406 no power

[jimmythom333]

Hi, i have a 406 hdi 2002 with 120000 miles, there was loads of black smoke coming out the exaust and there was no power above 2000 revs, i took it to my local garage and they plugged it in to a diagnostic machine and two faults came up (Egr valve and Airflow meter), so i got them replaced but the car is still the same if not worse, do you think it could be the turbo, can anyone help please.

Thanks Jimmy.