Q: Starts then dies

There are a number of things that may cause the symptoms you describe. Without additional detail as to the year, make and model of the vehicle, this may be difficult to diagnose without looking at the vehicle. A few different things will usually cause the vehicle to start and then die. A bad ignition coil can cause this if it is beginning to fail, resulting in intermittent starting problems. A dirty or faulty mass air flow sensor, may also cause this kind of reaction. The mass air flow sensor is a unit that measures the volume of air entering the motor and relays this information to the computer in order to cause the computer to make the proper air/fuel adjustments. A bad fuel pump or fuel pump relay may also cause this kind of starting issue as a result of the engine starving for fuel. Additionally, a vacuum leak may cause this to happen as well. I would suggest having a professional from YourMechanic come to your location to diagnose and inspect your vehicle to determine the proper solution to this.