Hello timbo23, you might also try using a high grade fuel such as Shell V Power or BP Ultimate and run that for a week or so. Then afterwards always use a decent quality fuel such as Shell or BP 'normal' diesel. Of the 200 litres or so of Shell diesel I use per month I put in 45 litres of Shell V Power. I believe it keeps things clean and helps smooth running. I also get 50mpg+ from my Skoda Superb. My daughter had a Golf a while ago that started to feel 'lumpy'. She had a 50 mile daily commute so it was getting used properly. Turns out she was buying supermarket fuel at the cheapest place in the area. I filled it with Shell V Power, she ran it all week and it came back to life. She then continued with normal Shell diesel for years with no repeat of the problem. Good luck. Concrete