it could be the exhaust re circulatory valve, it sticks. I am not an expert at all, and others could give you a better idea. Anyway, it can stick open or closed, open and the exhaust gases go into the intake making it sluggish, closed is the worst, probably makes the car faster, but leads to overheating, intercooler can buckle and eventually turbo failure.
If it is this, it is an easy task, you need to remove it and clean it, use carb or brake cleaner. it is at the top back of the engine, 2 or 3 bolts hold it on, strip it and clean it. the problem i have read is caused by the infrequent oil changes (18000 mile) or should i say, not helped by the infrequent oil changes.
this may or may not be the cause, could be water in the diesel, not being buying diesel from tesco have you? alledgedly.
Rob, August 2007
