Engine Mechanical problem
1990 Mercedes Benz 420sel V8 Two Wheel Drive Automatic 250,00 miles

I finally got my old 1990 420 sel to start and now when you put it in gear it shifts reall hard, you feel it slam in gear.
When you let off the brake and hit the gas you get no response at all but it idles at like 30 to 40 mph.
I was told it could be one of 2 modules for the fly by wire . one on the motor and the other behind the glove compartment