I recently purchased a 98 4.6 HSE with 105,000 miles. I love it and it runs great. There are no problems except I am getting less than 10 MPG. I am driving it as easy as possible and the gas mileage is still terrible. This seems less than it should be getting. There are no engine codes or check engine lights. The previous owner got rid of the airbags and upgraded to 20 inch wheels. Could this be causing my problem? Will changing the O2 sensors help? Thanks for the help.