I was driving my 1999 300d today cruising along at about 50MPH when I heard what sounded like a bang or loud pop and there was a cloud of white smoke behind me. Now the car has almost no power and jerks and blows white smoke when it is jerking during acceleration but no smoke when running down the road. It no longer feels like there is any turbo boost. I took off the air inlet and I can see the turbo spins freely and the engine runs smooth at idle.
Top speed is about 60 MPH. There is no check engine light like there was when the cat converter plugged. I got a code then that said the waste gate was bad but it was a plugged converter instead.
The fuel filter was change just to make sure..but no difference.

 

Could the timing chain have jumped?

 

It surges sometimes like it has power so I don't think it could be the timing chain. Tomorrow I will try taking off the exhaust.

I am hoping it is something simple because this car is a bear to work on. Way to many electronic gadgets and not built as well as my old 240D

 

Found it! Thanks for the clue ForcedInduction
I followed the hose from the intercooler to the intake manifold. The hose was OK but I found that the pipe came loose from the intake manifold. There is a 10mm bolt that holds it in place that came out. I don't understand the loud bang or the white smoke but that sure enough was the problem.