The idle shutdown mechanism depends on how the ECM is set up... there are many ways this can be done. Running it at high idle might or might not override the idle shutdown, dependent on how the parameters are set. If you have ambient air temperature override, you can tape a hand warmer to the temperature sensor.
about 5-10 litres an hour does it get driven or left to idle
The idle air control valve on a Volvo S80 is located on the intake manifold. The valve controls the rate at which the engine holds an idle.
You need to clean (or replace - $200) the idle air valve.
Volvo A.B. and its shareholders.
For non fuel injected models, on the side of the carburetor there is an idle screw. Turning the screw slightly will raise the idle on your Chevy truck.
Volvo
Volvo is a Swedish company not Chinese
As far as I can tell, Iowa is not a no-idle state.
You need the Volvo software to do this. It's programmed into the engine ECM.
If the check engine light does not come on when your truck dies it's probably the idle air control valve
check airflow meter
No it will not. It only controlls the idle of the engine.