While driving, I had to slow down due to a driver that I was following approaching a turn. When we turned, the other driver took the turn very slow so, I also had slowed. At this time my entire car SHUT DOWN! I rolled to the side of the road waited a minute but, the engine wouldn't start back up? After about two hours, it did but, the car did the same thing about 3 miles later going over a speed bump - when I needed to slow down again! What's wrong??