I am getting horrible gas mileage. I cleaned my throttle body and my MAF sensor three times already. I took my car to Firestone to get a diagnostic and they said my car is running better than ever. My Service Engine light is not on and I wasn't able to pull up any codes.
When you say you are getting horrible gas mileage, you do not specify how bad. If another shop says it is running ok then it may be OK. If you are getting a drop of more than 2 to 3 miles per gallon in the city then you may be having an issue that would need a thorough diagnostics of your complete vehicle to see what could be causing the problem. The brakes could be dragging, the tires could be low on air or a different size, the engine could have problems with it that the computer does not detect, the transmission could be slipping or a number of other issues that could contribute to a loss of fuel mileage. Even added on body parts or aftermarket engine parts can cause this. I recommend you have a certified mechanic, like one from YourMechanic, come and do an analysis of your problem for you.
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