2003 Mitsubishi Galant idle

Do you mean the idle speed is too low and you have to hold the gas pedal down a little to keep the engine running? Was the battery recently disconnected or run dead?

You need a scanner to tell the Engine Computer to run the idle speed motor in and out. Years ago it was common for some air passages to get blocked with carbon but that doesn't happen much anymore. The motor can get gummed up and not turn. If there's an electrical problem that will be detected by the computer and it will set a diagnostic fault code related to that.