Gutless GT 1.9 Diesel

Afternoon to all ,

Just got my GT 1.9 Jtd back from the main dealer after clutch warranty work - the good news is the clutch is light and proper , the bad news is it is totally gutless below 2800 rpm and when it starts to go ok it chucks out loads of black sooty smoke , the way this thing runs now I am wishing I had put up with the heavy clutch ! I have rung them and they are going to look at it on monday

any ideas , pipe off etc ??

tia