Volvo Repair: 94 850, wrong diagnosis, awnser

Question
few skills 160,000 miles on my 94 v850 my car would die and not restart on the highway or right after i started it so i took to my local shop and was told it was the ignotion module and coil bought the part and had them put it in . my car ran fine for a week now its dying again execpt this time there is not a code to read and it will directly restart ? i have been told several different things that may fix it but without a code no real awnser. could it be a crankshaft positioning sensor? any help would be great  

Answer
Dear Jason,
          I'm not that versed in code procedures and you should bring car to dealer and get expert opinion.
            Don't get caught up in wrong diagnosis and pay for items you dont need.
            
                  Good luck ....Jason,
                    Bilbo