Throttle Position (TP) Sensor (Montero)
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.
Disconnect TP sensor connector. Check resistance between TP sensor connector (component side) terminals No. 2 and 4. Resistance should be 2000-4000 ohms. If resistance is not as specified, replace TP sensor. See THROTTLE POSITION SENSOR in REMOVAL & INSTALLATION article. If resistance is as specified, replace throttle body assembly.