Please help me. 2004 Audi a3 2.0tdi bkd white/grey smoke on idel and under load.

[John hughes]

Hi all, I have my beloved 2004 audi a3 2.0tdi bkd engine, its on 157000 miles, it runs a little lumpy, nothing to major, but on start up and under load it smokes a white grey ish colour and smells a little rich, when warmed up it tends to struggle a bit to restart. Can some one please help me with some advice,