If you clean the valves up and re-gap and it still dies it, The cam has ACR.. Sometimes the spring takes a hiatus and it won't stay in the correct position @ WOT.. It would definitely have the same symptoms as the ACR keeps the valves open a bit on the compression stroke releasing compression for cranking purposes,,
Once the engine gets going weights on the cam extend and return the cam lobes to the full compression position.. Missing or busted springs are a cause of symptoms you are seeing. LOOK at the cam in the picture to show what I'm talking about..
Ignition timing could also cause the issue due to firing too early.. The rotation of the ACR also affects that too since the whole cam lobe spins independently of the inner shaft..