The 722.4 operates the same in the W210 as it does in the W124. The control pressure cable adjusts how late the shifts occur. The tighter it is, the later the shift. The vacuum adjusts how firm the shift is. More vacuum = softer shift for lower speeds and to prevent clunks on downshifts as you slow down.

If the shifts are all at the high RPM, check that the kickdown button isn't stuck. You might also try unplugging the solenoid on the transmission to see if it makes any difference. If the solenoid is stuck open, or if something is shorted keeping it energized, the shifts will all be at very high RPM as if you have it floored.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

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1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]