[mr_tw]

it's a possible solution, when your O2 sesors go, then the engine thinks that it's running lean and dumps in toomuch gas so you should be getting less mpg as well, obviously the extra gas could be whats causing the problem on your car, i would suggest just changing them yourself, all you need to do is find them, when i changed mine (different motor) all i did was put my hand on the exhaust pipe right after the exhaust manifold and felt down thepipe till i found it then it's just a matter of unpluging the old one and unscrewing it and then doing the reverse with the new one (obviously you screw it it then plug it in) the sensors are quite cheap, and you may need to remove the tire to get in there, but it's overall an easy job and you'll save yourself the 75$ an hour that the dealership charges you (the sensos should cost less than that lol) but good luck