The engine will start and run fine at different speeds for awhile. Then one cylinder will stop firing, then another, and then the engine dies. Restarting usually occurs after waiting a minute or two. It may restart and run ok for a while. Another time, the engine then ran roughly and lacked enough power to move the car. When this occurred, it was towed to the dealership. Other times it runs as though it is functioning properly as it did over the last seven days when the technicians tried to replicate the problem after it was towed to the dealership Drove home with it, about 55 miles. Stopped the engine to get something at WalMart and the engine would not restart. None of the cylinders fired. Walked home. Suggestions? The Volvo repair shop is quite a distance from home.