I live in Hawaii, usually ambient temp here in summer is around 85-88 degrees, little cooler in our "winter". BUT, the traffic here is horrible in rush hour. I've found that my 2003 XB9R will sometimes do the exact same thing...stumbles like she's running out of gas, then just dies. If I let her cool off 5-10 minutes OR if I keep at least more than 1/4 tank gas level she doesn't shut down. It kinda sucks but I always fill up around 100 miles and that keeps her from dying on me in heat and traffic, even though I know I have approx 1.3 gallon left. BTW, I tested my theory four different times by riding early in the a.m. and later at night when it's cooler, with about a gallon in the tank. Normal low fuel light, all the way to .3 gallons when I hit the gas station and no shutdown.