My 1990 190E 2.6 (190,000 miles) has suddenly decided to run through all the gears prior to hitting 2000 RPMs. To gain any level of performance, I have to manually shift through the gears. When coming to a stop in the Drive position there if an audible downshift thunk at or around 5 MPH.

I have performed the following to try to resolve the problem:

Replaced transmission fluid (Dexron III) and filter.
Replaced modulator valve and vacuum hose.
Checked control pressure cable.

The only maintenance that has been performed on this car was adjustment of the EAH valve a few weeks ago. This problem started three days ago.

Any help would be greatly appreciated.