I just replaced fuel pump on my 94 850. If look in postings you'll see it. I had very similar symptoms: bogging hesitation. Then one day it stopped and wouldn’t start. I replaced the pump and found out that small rubber hose inside of the pump housing that connects pump to the fuel line got disconnected from the pump. Pump was pumping but only some fuel was getting into the fuel line and the rest was going back into the tank. I think that is why it feels like the car is loosing power and missing. It is not getting enough fuel. Try taking out the pump and check that hose. Good luck!