I've found that on my 240D I can leave the idle speed adjustment adjusted UP but not PAST the point where it starts to affect the idle.

Using this, it baiscally holds the linkage a litlte bit "on" but doesn't change the idle speed noticeably.

I've noticed that when you let off it will slowly return to idle (not quite as fast) and this makes it a lot easier to drive.

The dashpot (of course) would be the RIGHT way to do it...just offering an alternative.