273 Won't Run When Warm - Carb Issue?

This same thing was happening to a friend of mine recently. I looked everywhere trying to figure out the problem and eventually decided to ask him if he used a higher temp spark plug when he replaced them shortly before all that started happening. I know it might seem left field, but turns out the higher temp plugs were holding enough heat in his engine that it was keeping him from being able to restart it whenit was hot. There was a lot more of thought put into my reasoning at the time, but long story short, he replaced the spark plugs with a lower temp plug and the problem went away....