Jaguar s type 3 litre 1999 running badly, has been stood for 2 years, was running lumpy when stood up, hence why I bought it so cheap! have changed spark plugs, air filter and one coil pack and 1 lambda sensor needed changing. has passed mot and the emisions were ok. car on tick over sounds as though its not firing on all six, when you put your foot down its good, when you want to cruise at 50 it jolts and shudders as if its miss firing. strong smell of petrol from exhausts when driving along, so my friend said who was following. any help on what to check next would be a great help