A slight vibration at idle could be a misfire that the computer isn't reading. Bad o2 sensors can also result in bad gas mileage. Usually a bad O2 Sensor will give a Check Engine Light.
The best option would be to have someone scan the computer for codes, or scan them yourself if you have the tool.
A standard tune up with spark plugs, wires, and rotor cap and button are a good place to start if you haven't done this recently.
Thursday, March 14th, 2019 AT 2:50 PM