Q: Dies sometimes while idling and belt broke started smoking and died

The serpentine belt can break simply because it has reached the end of its service life. Another cause of breakage is if one of the driven rotating elements seizes. That would cause the belt to suddenly stop on that element which could shred the belt or break it. Any of the many rotating elements could cause this, not just the belt tensioner, and thus the entire circuit that the belt travels has to be carefully inspected. The reason you saw smoke is the serpentine belt drives the water pump. Once the water pump stops turning, the engine will get very hot and you may see steam escaping from the cooling system. Obviously, do not drive the car without a belt as the lack of a water pump will cause overheating. If you request serpentine belt inspection/replacement a certified Mechanic, dispatched by YourMechanic right to your location, will pinpoint why the belt broke and determine if there are any seized, or rough, rotating elements in the belt circuit that need repair. Once the engine is running properly again, the same mechanic can diagnose the stalling issue, if the issue still exists. If you have further questions or concerns, do not hesitate to re-contact YourMechanic as we are always here to help you.