That's not a very clear photo Don, looks more like a clip to me. As long as you didn't alter the adjustment screw on the throttle butterfly it's retrievable.
Like Tony says ^^^^^ above, there isn't a separate idle speed control, it's set by the ECU. When you say cold idle is high as well, what are you calling high?
It does sound a bit like the speed signal being lost to the ECU, if you can get the fault to happen again, read the codes and see what they show.
https://www.volvoclub.org.uk/faq/Eng...InjectionFault
That's the section you need for the actual codes on yours, read the section above it on how to access the codes if you're not familiar.
