I just got back from a 45 minute ride in the rain at 70 mph. No stalling. Not even a hiccup. I wonder if the fact that I just installed a K&N air filter has anything to do with it. Most people's initial thoughts would be no. However, the fact is that the stock air filter is paper. Paper is prone to getting water logged, which then would prevent air from passing. It turn stalling the bike. The K&N I installed is oiled woven cotton. I also used the K&N sealing grease that goes around the perimeter of the filter to prevent leaks.
P.S. My bike has never had a stalling problem in the first place. Also, I still have the charcoal canister on too.