Bmw 525: I have a 525 on a 51 plate. When the engine is cold at idling speed, the running value of one of the pots is higher than the others and then eventally is shuts down. Soon as you switch the engine off and turn it on again it's fine. It never happens when the engine gets up to temperature or when you are driving along. It only happens when the engine is cold and at idling speed. I have a fault code P313 which means a engine misfire. What could this be?