I have a 91 735i, 4sp auto, 3.5lt. Usually around constant speed of 40-45 the tranny will downshift then up then downshift an sometimes it will downshift to 2nd which scares me thinking it might downshift to 1st an explode the engine or tranny. If I engage cruise control it does not downshift. This does not happen all the time but when it does it can be very severe with jerking and slamming into an out of gear. The trans has a dipstick and the fluid does not look bad. I replaced head gasket and it was doing great for about a month and then poof the downshifting started, any ideas would be great! Ken