If you haven't had an oil and filter change recently do it now it is absolutly CRITICAL for them to run properly,we had the same problem and it cured it,short journeys especialy ruin it,it could be other things but if it aint been done it needs it and it will only do good anyway.I also flushed the engine with flushing oil as well but I'm fussy,you cant put just any old 20/40 in these days the engine relys on the proper oil.
Rich, July 2011
