Hyundai Elantra 2000 automatic, stops engine after few minutes
 

Hi, I have a Hyundai Elantra year 2000, automatic 2000cc... last week I chance the tank and the valves, everything was ok, but 2 days ago, the car begins to stop the engine after few minutes or runnig, I don´t know what it is, I need help. The computer says that it is a valve that is open, but I change both valves that the tank bring.

Makes no sense to me. I've worked on quite a few cars in over the years but I have never heard of that.