I have a 2003 Ford Explorer V-6 Flex Fuel, with 98000 miles. It has recently started to make a popping sound when you make a sharp turn. It is loosing gas mileage by half. It seems to me that it is stuck in 4 High. But the light on the dash is off. I've tried pushing it, and even disconnecting the battery to maybe reset it. It hasn't worked. Any ideas if it might be a sensor or something else?