first check your fuses, there is one in the fuse box for the downshift. there is a solenoid valve at the rear passenger side of the transmissionn that controls the downshift function. i have seen the wire that goes to the solenoid rub off the insulation and the wires inside will contact ground on the transmission cross member and blow the fuse. also look at the switch under the accellerator pedal, the floor mats can bunch up in that area and cause low power and no kick down. hope this helps.
Ray
let me know if you have more questions
mercedessd@cox.net