This sounds a lot like a problem my little brother had with his car. In cold weather especially it would rev the engine by itself then die. It turned out his was just old and due to accumulated wear and grime, the idle "choke" system was sticking, and the cold just made it worse(shrinkage making it bind). I would open your hood, have someone start the VX, then see what cables and linkages the computer is making move when it starts up and clean and re- lube them. That's what worked for him.