Volvo Repair: 2000 S80, light switches, minute period

Question
I recently purchased a used 2000 S-80 2.9.  It  ran well for the first 2000 miles and then last week, while driving it the sunroof switches, interior light switches, and door lock switches wouldn't work.  The next day the switches again wouldn't work and while I was driving, it cut out at low rpm repeatedly over a ten minute period.  After resting it for forty-five minutes it worked fine and has since although the light switches have worked on and off.  Can you advise us?

Thanks,
John

Answer
the sunroof and lightswitch problem could be a bad alarm siren which can lock up the upper electrical module causing these items not to work.the stalling could be a bad throttle unit or dirty throttle unit or the car may need a software upgrade to a control unit to help with this.