Hi,you say that your carbs are fine,I thought this when my bandit did the same thing. I changeed the plugs coils leads and 
caps but it made no differance to the running.I took the bike to the garage and he suggested that i have the carbs ballanced
when it came out the bike run like new and the problem solved.Hope this helps it is worth getting them checked.
                
 Colin
                
 January 2005