Have you run some cleaner through it? Like a nice bottle of Techron or Lucas injector cleaner?
Ya might need ta pull them out and clean 'em, or get them rebuilt.
I get no less than 28MPG in my RS DOHC in city, and I do some... fun driving

ariesdude wrote:Another unlikely scenario that happened to me and reduced my gas mileage a lot - sticky handbrake and corroded calipers. The brake pads were held uneven because of the calipers and the hand brake spring was not releasing as much - so i was driving with the brakes on all the time - but it still gave me 24MPG - once i cleared the problem - it jumped to 30.