A couple things to check, one being your ignition battery. Even though you said it was charged, and showing good voltage, it could just be weak cell(s) that are dropping rapidly once the ignition starts drawing power from it. Had a friend have this near exact situation the other day. If you have another battery, swap it out and test run it again.
Check your carb screen for debris.. some crud in your carb screen could be slight enough to run okay, until it really tries to pull a good draw of fuel. Its somewhat a leap to go from good running, to next running such drastic performance drop, calling the carp bad. But not out of the realm.. that would be the final thoughts, once all the typical, more simple problem solving has been exhausted.
May also go over your fuel system, most importantly your clunk, pinched or pierced fuel lines etc..

Good luck