Slowing to a halt the engine revs drop to zero. Rain, shine, with the car hot or cold, with ac on and off, with steering applied or not, brakes applied or not. There seems to be no pattern. It can go a day and not do it at all then do it five times in less than five miles. Its been regularly serviced and otherwise thoroughly reliable the 13 years (!) Ive had it. Any suggestions much appreciated.