Hi can any one offer advise please. Have a 406 HDI 90 (51 plate), 85000 miles. The engine is running very lumpy at tick over but runs sweet from there. Its not too good on fuel around 40mpg. Dealer says its injectors but at £1000 its a lot of money to find its some thing else. Smokes a little but none more than you would expect. Just had a head gasket, but was running like this before.