tdi 140 juddering

hi, i have recently had a new turbo fitted about a thousand mile ago. the car was fine at first but now it s started juddering or kangarooing under 2000 revs it seems to have lost power on acceleration and is also puffing black smoke out at gear changes does anyone know what could be causing this thanks.

You need a code read to point you in the right direction.

thanks for the reply martin i will take it back to the garage who fitted the turbo on monday.do you think a pipe could of come off somewhere