Engine performance and gas mileage go hand and hand.  If your vehicle is running inefficiently, you will not experience increased gas mileage and could possibly be doing damage to your engine and components.  We can not stress enough how regular maintenance will prevent unexpected and costly future repairs and roadside breakdowns.  Here are some recommended maintenance items.
1. Regular oil changes.  Pushing dirty oil through your engine and components is harmful to the engine. 
2. Air Filter inspection and change as necessary.
3. Fuel injection system serviced every 15,000 miles to prevent carbon build-up and deposits that restrict fuel flow and degrade engine performance.
4. Transmission fluid and filter replaced every 30,000 miles to ensure proper lubrication, preventing damage and ensuring smooth performance.
5. Timing Belts changed every 60,000 miles or as recommended by the manufacturer to prevent unexpected failure that can leave you stranded and cause severe engine damage.
6. Maintenance tune-up performed as recommended by the manufacturer to ensure longevity, optimal performance of your engine, and improved fuel economy.

We recognize that  it is frustrating to have your vehicle diagnosed and repaired only to have the ‘check engine’ or ‘service engine soon’ light come on again.  The function of your vehicles computer and the  'check engine' or 'service engine soon' light is to warn you of a problem.  This might be related to the repair or it might be an entirely different problem. If there are several issues with the vehicle that the internal computer is detecting, the light will come on sometimes right away, sometimes later on down the road. You will need to have the vehicle re-inspected and possibly diagnosed to determine an additional problem.

Overheating is caused by anything that leads to a loss of coolant, prevents the cooling system from getting rid of heat, or causes excess heat in the engine itself.  There are several components or conditions that can cause overheating;  water pump, radiator, heater core, hoses, freeze plugs, head gasket, radiator cap, deposits and build up, thermostat, cooling fan, fan clutch, shroud, fan belt, ignition timing, or exhaust system.  It’s important to discover the cause of overheating before you become stranded and do major damage to your engine.

Most hose manufacturers recommend replacing hoses every four years and V-belts, every three years or 36,000 miles. The incidence of failure rises sharply after the forth year for hoses and third year for belts. A typical serpentine belt lifespan is about five years or 50,000 miles. Serpentine belts are thinner and more flexible than V-belts. They run cooler and last longer, but they cost about twice as much to replace.