Why does your Mitsubishi diamante 2002 idles at 3000 rpm when cold?

The high idle of your 2002 Mitsubishi Diamante at 3000 RPM when cold could be due to a malfunctioning idle air control (IAC) valve, which regulates the amount of air entering the engine during idle. It might also be caused by a vacuum leak, causing the engine to compensate for extra air. Additionally, issues with the engine coolant temperature sensor might lead the engine to misinterpret its operating temperature, resulting in a higher idle. It's advisable to have these components checked for proper function.