Leaking turbo ducts cannot drop the idle RPM to 200RPM & stall out;

Check the mass air flow (MAF) sensor which is install in the duct comming out from the Air Filter; possible causes: loose electric connection to the sensor; dirty sensor because of broken / poor filter element paper;

Fix ...

I had the same problem;

This is an other poor design fault of volvo Engineer.

Cause: there is a bunch of fuel tubes near the rear LHS wheel arch; These tubes are held in place by a little PLASTIC clip. This clip is broken with time under vibration condition; When you car runs over a small hump ...