well, I change about 3 liters every 25kmi, so none of the fluid should be all that old. I really thought it could have been a plug adapter problem, the connector had a small amount of oil.... There is no oil in the tcu, and after replacing the connector, it runs about 30% better.
I guess I will change more oil this weekend, replace the spring and then bring it in to check the adaptation values and go from there. I suppose after 165kmi, it could be more than just a spring.

The frustrating thing is that noone else seems to have had those symptoms. A transmission that shifts into all gears, well below 2500 rpm, and very hard at higher rpms...

Anyone knows of a good shop, or how to find a good shop in Houston?

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2008 S550
2010 GLK350
1997 E420 (retired)
2005 CLK500 (retired)