My Jetta will randomly shut off when coming to a stop or driving slow. The EPC light will come on and the car will try to spin over, but never fire. Sometimes it will fire back up, sometimes it will not. When it does fire back up, the EPC light stays on. If it sits a little while and I crank it back up, the light will not always come on. I had it read with a code reader and it said it was the engine speed sensor and something about the coolant. What would make it do this and what will it take to repair it?