Yesterday while driving my 99 F-350 (V10) Had an check engine lite to come on, Took it to advance auto they put their computer code reader on it. said that the right & left bank of the engine was running lean? what would cause this? & how do I fix it? Also I think the gas mileage has gotten worst. I normally get around 10 miles to the gallon which isn't good to began with.the guy at advance said to use some injector cleaner in it. Any help would be greatly appreciated Thanks Dave F.

 

First step would be to visiblymake sure there isn't any unmetered air (vacuum leaks) entering the intake..Then before any extensive searching or additives, try using some spray 'throttle body cleaner'and 'carefully' clean theMAF (mass air flow) sensor with a short shot/s of cleaner and allow it to air dry.. Dust/debris can collect on thehot wire internal to the MAF'insulating' it from the air movement through/over the sensor wire changing the flow reading values.. Clear the code and see if the CEL returns...