Lately I have been noticing my transmission shifting at weird points. The transmission always shifts before 2200RPM, even at WOT. Sometimes the transmission will shift around 1700-1900, but usually the shifting points for all the gears is about 2100 rpms. It shifts so fast into 4th gear that hard acceleration as to highway merging makes it very hard, it does not down shift from 3rd. I did a transmission fluid and filter change about 4 months ago and I thought I noticed a small slip on some gears, now that has disappeared. Manually shifting from 1st to 4th the transmission gives me no problems, it shifts great. Also my kick down switch is not working. I replaced it with another used unit but still does not work. I have that part on order. I tried to find writeups on this issue but only find ones where people have their transmission shift at high rpm. I'm thinking its a vacuum issue on the transmission itself.
From my understanding the bowden cable determines the shift points. The position of the throttle arm determines how much the bowden cable is pulled which I assume adjusts some lever on the transmission. Therefore the shift timing should be directly proportional to the position of the throttle pedal. I.E. the further down the pedal is pushed, the later the transmission shifts. I believe the lever on the transmission that the bowden cable moves is connected to a vacuum valve. Do you think it could be leaking? This just my theory. Any help is much appreciated!!

I'm not familiar with the E300 but I don't recall any 722.4 in which vacuum affects shift points beyond some models with a sport/normal switch. Step one for me is to ensure proper relaxed tension in the Bowden cable and that the adjustment mechanism isn't loose or broken. Sticking my neck out further, there are no vacuum systems inside the transmission. The vacuum modulator on the port side takes a signal from the VCV to set a signal pressure, but the vacuum part of it stays outside the transmission.

Sixto
87 300D

I had this sort of problem where the shift point was always 1000 rpm short on WOT, to remedy this I had to drop the pan to find my problem - the lever where the cable attaches to was sort of dislodged and the cable itself was not properly seated.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)