Im asked a similar question acouple weeks ago and replaced everything 'cept the spark plus wires. Im still getting the same gas mileage. The only time I got better gas mileage was when I drove straight for like 3 hours. got around 230 at little below half tank. Is there anything we can do ? When I was at kragen auto parts the guy asked me if I had a lead foot. I said sometimes but not usually. So would that be a problem, our driving style ???