Poor Fuel Mileage

WARNING: This page does not describe the selected car, but rather 7 other vehicles, including the 2003 Mitsubishi Outlander, 2003 Mitsubishi Montero Sport, 2003 Mitsubishi Montero, 2003 Mitsubishi Lancer, and 2003 Mitsubishi Galant. However, it is still accessible from the selected car via links, so may be relevant.

Check fuel system enters closed loop operation.
Check engine coolant temperature sensor.
Check intake air temperature sensor.
Check barometric pressure sensor (if applicable).
Check manifold absolute pressure sensor (if applicable).
Check throttle position sensor.
Check front Heated Oxygen Sensor (HO2S).
Check fuel pressure.
Check ignition timing.
Check camshaft timing.
Check compression pressure.
Check for fuel injector leakage.
Check fuel system for leaks.