Scubasteve
Leaving Skid Marks
I would do a boost leak test. I got similar figures with a split vacuum line.After doing the major service including plugs, air filter and O2 sensor I have not seen an improvement in fuel economy. I do have a hole in the exhaust which could explain why but I am only managing about 350 a tank on a stock tune. I could get close to 500ks when I first got the car.