I do have a gauge and I have tested the modulator.

Going back to when I had the bad modulator on the tranny. It would shift very late and at very high rpm only. It did this whether the vacuum line was attached to the modulator or not.

Immediately after installing the modulator, it started shifting very early and at way too few rpms.

I agree that it seems that something in the installation went wrong but what? You just unscrew the old one and screw the new one in. The only thing I can think of is the spring and rod that goes between the modulator and whatever is inside the transmission. I remember removing the old one and the rod and spring fell to the ground. I then attached them to the new modulator and installed it.

I just don't know what I could have done or not done that would cause this problem.

__________________
1993 W124 300D
-297K on the clock as I type this.