So I took it back to the shop that installed it for me armed with the pages from the factory manual regarding set-up, they were able to adjust the modulating pressure properly. They discovered my VCV on the side of the injection pump was not functioning properly and replaced it with a slightly used one that they had in stock.
Shifts now like it should.
I ordered a new VCV from Mercedes that I will be installing.

__________________
91 300GD SWB with transplanted 87 OM603 turbo motor