Q: Car turns off for a second or two while at a stop

This may be caused by many different things, however what is most common given this kind of symptom may be a dirty or failing idle air control valve. This is a unit that monitors air intake as it is mixed with fuel prior to being injected into the engine. This unit relays specific details to the computer that uses this information to develop the proper air/fuel mixture to be injected into the engine. When this is not working properly, this can cause an improper air/fuel load to be supplied to the motor at low speeds such as when sitting at a stop light. This type of problem may be worse when the vehicle is in gear or under a load than when sitting at idle. I would recommend having an expert from YourMechanic come to your location to properly diagnose your engine issue and repair this.