I revved my outboard on flush muffs! Big mistake. Help!?

Hi, I have a Johnson 50 hp that runs good. Well, ran good. I hooked it up to flush muffs and revved it. I know, I shouldn't have done that. I feel like such a fool. Anyway, it revved up really loud and shut off. I gave it a break for a few minutes, but now when I turn the key to start it, it starts and will only run for like three or four seconds and then shuts off. What did I mess up? It's a 69, but has always run well. Does it just need to sit for a while, or did I mess up the flywheel or something or overheat it? It's just seems strange how it will start and then cut off. I'll crank it, it turns over, fires up and then after a few seconds just dies! Why?!?