Check the battery. I have a 94 850 turbo and experienced the same thing recently, Had the battery and alternator checked at discount auto, both tested fine but the tech said the battery was low, after putting on the charger it was fine. I still opted to get a new battery because I had not checked the water level in two years (maintenance free still need water added once and a while) and it had lost water to about an inch below the top of the lead inside. Figured the problem would just continue to recur.