Help!!! Motor dies when coming to a stop?

Hey everyone.I'm new here but I want to share also what happened to my car I have a 73 dart swinger 318 and had the same problem.Drove around for about 20-30 minutes,come to a stop light and engine would just die.the temp indicator would say almost 200!So there i'd be with the hood open and with a wet rag on the coil.Bought a new coil and GROUNDED well the ballast resistor to the firewall ever since it's been running great.