[W126 Coupe] kick down mixture richener

[Shayegan, Richard]

The talk about the fact that at full throttle the mixture gets richened
got me thinking, what is utilized to the richening? Is it possible that
it richen too much? I ask before setting the mixture leaner (even to the
point where idle is rough) gets me faster flat out acceleration times,
but setting it richer gets me better throttle response and better wide,
but not wide open, throttle acceleration.

Also, I've heard that on some newer cars there are electronic ways to
adjust the stall speed. Is there by any chance some mechanical or vacuum
way to do this on our cars?