my 1999 12000 mile clk has just developed an intermitant gear change problem if im say doing 70mph and kick down or gearbox changes down to 4 or 3 rd it wont change back up again just sticks in 3rd or 4 th till i stop. also so does the same if i change down manualy with tiptronic go back into drive reads d but wont change up. but then if i go from s into w mode changes into top perfectly every time.. then next day is fine again really strange any ideas please.