98ml320 slams in+out of different gears

[johnflight1]

98 ml320 92,000mi .intermitently slams in to different gears at will! highway or city driving. you can be going along and then slam 6000 rpm . now it is doing it more and more frequently.now it wont go into overdrive at all till the next day when it cools off. and it also wont down shift when you come to a stop. it may be a sensor of some sort because the engine is running rough while all this is going on. the next day you start it up and all is fine. no dash idiot lights. never changed the fluid mbz says change at 100k. thanx John