No idea what a Ad 11 Johnson is but I’m struggling with this
being an ignition problem. You say “coils & condensers”. If there is an
ignition for each cyl. it doesn’t seem likely both are dropping out & coming
back at exactly the same time unless there is some kind of ignition cut off
shutting down the motor. Fuel seem to be a more likely the issue. As you
have changed both the carb and the tank that leaves me to suspect what is
in between. My suggestion would be to take the fuel line off at the carb and
pump up the tank to see how much fuel you get.
Tubs.
A "Boathouse Repair" is one thats done without having tools or the skills to do it properly.