MPGs

This sounds like you got a lot of carbon built up in your cars exhaust system. This could also cause your car to use excessive amounts of gasoline. Try taking your car out on a back road and put the gas pedal to the floor. This will blow alot of that carbon right out of the system. I would start at like five miles per hour and step on it until you reach a speed of about seventy to eighty miles per hour. This might not sound like i no what im talking about, But just try it and watch how much better your car runs. good luck.