This bike stopped idling about 4 months ago. The bike starts with choke and runs okay over 3000 RPM. No power when you let out the clutch from stop and almost stalls. It also does not idle down between shifts, will hang up around 5-6K rpm. Has been back to the dealer once and he changed the needle valves and cleaned the carbs. Ran good for two to three weeks and back to the same. He says that it is the ethanol in the gas. Has anyone else had this problem or could it be something else.