Poor performance on kickdown.

Hi, The 740 accelerates smoothly until kicked down, then the revs climb to 5000+ but the speed does not change. The car then runs very rough as though 2 cylinders are not working until the ignition is turned off. The car starts immediately & is back to normal, until its kicked down again. The car was recently serviced & no codes are shown in the ECU. Any suggestions? Any help would be appreciated. Thank You.

Have you run this problem by the folks at roadfly.com?