Thanks for the explicit notes.
I have disconnected the little black wire that comes up from the Delay Shift solenoid and driven it around for a few days.
So far, I have noticed no perceivable difference how soon this delayed shift takes place, warm or cold engine temp.
Reconnected and run a while (100 miles plus) and then disconnected it again, and still it persists.
I will try the vac testing in the next few days and report back...
'90 190E 2.6
'87 300TE (gone to car heaven)
'84 190D (passed along...still in the family and used on a daily basis)