Volvo 2004 s60 idle drops to 500 rpms when you stop?

A 2004 Volvo S60's idle dropping to 500 RPM when stopped could be caused by several issues, such as a vacuum leak, a malfunctioning idle air control valve, or dirty throttle body. It could also indicate problems with the fuel system or engine management sensors. Checking for any diagnostic trouble codes (DTCs) can help pinpoint the issue. Regular maintenance and cleaning can often resolve these idle fluctuations.