I have a d4d. Recently posted about how it will only run on good fuel. Basically it has a variable vane turbo which gets clogged with coke deposits easily. Run it on premium fuels and it clears it and keeps it clear.
Also a bottle of turbo cleaner once in a while.
Ah! Interesting to know. Thanks for the advice. When you say 'premium' do you mean just decent non-supermarket stuff, or specifically the premium stuff at the pump (VPower or Ultimate)?