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Q: Bad gas mileage, high idling

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I'm getting really bad gas mileage while driving my truck. It has now dropped to 7 MPG. When I'm driving on the highway, it runs great. However, it is idling high at the 1000-1500 RPM range. When I'm starting it up, especially when it's warmed up, I have to floor the gas pedal. It starts to sputter a bit before it gathers power. I've been told that many things can cause this, from throttle position sensor, MAF sensor to fuel pressure regulator etc. What do you think I should do to improve the gas mileage and overall performance of the vehicle?

A: Idle speed for your vehicle should be betwe...

Idle speed for your vehicle should be between 725 and 750 RPM. So, it is idling high. Common causes for this include vacuum leaks and a faulty idle air control (IAC) valve. Either of these issues could also affect fuel economy. However, there are many other potential causes as well. The first step is to retrieve any stored Diagnostic Trouble Codes (DTCs) which serve as a starting point for any further diagnosis. I suggest you have a trained professional, such as one from YourMechanic, diagnose your poor gas mileage and repair your vehicle firsthand.

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