Trevor, there is no choke as such on this model, it has an idle control valve, that is controlled by the ECU these valves do tend to get gummed up with sticky petrol deposits, you can normally clean them with a spray carb cleaner, but the problem could be with the engine coolant temp sensor giving the wrong info to the ECU and it commanding a higher revs than normal making you think the "choke" is stuck on!!
nigel
February 2010