For anyone still reading..
I found out what the switch on the 190 throttle does. It is for the transmission.
When off the throttle, and switch is activated, shifting from 'D' into, say, '3' will cause the car to jerk straight down into 3rd gear (presuming you're in 4th).
When on the throttle (switch not activated), the car will not jump straight into the selected gear, but instead seems to slip until you bring the revs up enough to engage that gear. Weird, but it's definitely the switch that does that, and it's very noticeable.
I don't think there's any problem in adjusting the throttle so the switch isn't activated, I have run my car like that for a few months.
2.5-16v 1990 90,000m Astral Silver
2.0E 8v 1986 107,000m Black