I still think it's the coil because it occurs after significant run time (45 minutes). A float bowl has nowhere enough fuel for it to run that long before problem begins.
New coils have been known to fail. Have it tested, cold and hot.
A friend of mine had a new tractor that would idle perfectly but choke on itself under load, hot or cold.
The dealer etc couldn't figure it out. Changed about everything.
Ended up being a piece of metal swarf from some drilling process had gotten into the fuel line. At idle it would let the fuel through. When you gave it throttle and the flow increased it would draw it closed like compressing a spring.
Cost, hundreds if not thousands to find, repair was free.