I have only been able to find two threads where people were having a similar problem and neither had the solution. I have a 2005 Jeep Grand Cherokee Laredo V6 AWD that has no MODS all stock. Newer plugs, good oil, newer battery. I used to get around 16mpg.... I recently noticed I'm in the 7-8mpg range. I've ran an injector/fuel system cleaner and tried filling up at different gas stations. It is not ethanol. She drives great with good power and no vibrations or odd feelings. Nothing. O2 sensor without a light? Cat converter? The air filter looks pretty good. Any experience is much appreciated especially first hand experience. Thanks everyone.