I have a 1987 300 SDL Turbo and seem to be experiencing a loss of power. In addition to this, the exhaust emits a tremendous amount of black smoke. So much in fact that the rear bumper and the trunk above the exhaust pipes is covered in black soot. The turbo has been replaced once already. A couple of years ago, Mercedes made a change in the exhaust/turbo system. They removed the trap oxidizer and essentially put in a straight pipe. Do you think I need to replace the turbocharger. If so, what could be wrong with the turbo? Could there be something else wrong with the car? Is there a reputable place you recommend that could rebuild the turbo for me?