Dear Doctor: My 1999 Dodge Ram with the V-8 engine used to average 9 to 10 mpg around town and 14 mpg highway. But now the gas mileage has dropped down to 12-mpg highway. I use synthetic oil and keep 50 pounds of air in the tires. I also use a high-performance air filter. What should I do? Mike
Dear Mike: As we’re all paying closer attention to fuel mileage there are many items to look for that can cause poor gas mileage. We need to look at everything that controls fuel management, including the thermostat and oxygen sensors. Sensors do get lazy and wear out. If everything else checks out, there’s a good chance that the injectors are dirty. There are a few companies that have professional fuel-injector cleaning products that work well, but this service has to be performed by a technician. Do not waste your money on a fuel-injector cleaner that goes into the gas tank. This will not clean injectors that are causing problems.