I'm surprised no one has mentioned timing! Is it possible you have weak advance springs causing timing advance at hot idle? Or vac. advance canister that sticks? I would put a light on it and make sure timing has not moved when it idles fast.
I did, check post #23. :) You are correct though, everything must be right in regards in to timing before idle mixture can be set. I have to assume in troubleshooting posts as I can never know everything that's going on. I try to use every sense that I have... I can't do that over the internet though.... :)