I had idle issues, where the idle was uneven, which was massively improved by simply removing the ICV, blasting it with carb cleaner and refitting.
A more recent idle issue, where the idle had dropped, was cured by adding a petrol system cleaner additive.
This has various diagnostics and suggestions for idle problems;
https://www.volvoclub.org.uk/faq/Eng...#Idle_Problems