BTW, I may not be understanding.... do you set the idle, and then it does not hold there later? Is the idle being initially set with the engine just partly warmed up?
I think you might not be, sorry if it wasn't clear and I'll explain better.
Fully warmed up with a totally stock unmodified Edelbrock 1406 with electric choke.
Very slight play in the shafts (maybe 5-6 thou) and a couple of years on the carb.
All ports either used or blocked (that one port in the pic is the blocked off non ported vacuum)
No intake leaks or odd stuff with the PCV.
Just simply that the throttle hangs just slightly above whatever I set the idle RPMs at until I lightly tap the pedal, and then it comes right down where it is supposed to be. (800 RPM) or 850 when it hangs.
I was thinking that equalizing the spring pull on the linkage might take care of that, and that even though the carb doesn't seem worn at all it still may be the off center pull on the linkage causing it.
It's really a very small deal, but it bugs me when things like idle speed vary from one stop to the next. :D