Peter Thanks for the reply. I have tried what you recommended, and the interior air circulation does help, although as you will be aware, this function is on a timer, which defaults back to normal after about a minute. I have made some enquiries, and I am being pointed in the direction of the emission valves. Apparently there is one on either side of the engine. I have been told these carbon up through time and stick open, giving the condition I am experiencing. I have also been told it is about 1k to change them. Regards, Quinny