A few suggestions,

I had a similar problem with poor idle in flight, almost the same symptoms (high idle setting, ok on ground with full tank). I was running 10% fuel with 20% oil and just a little rich on the high end.

Poor idle could be related to plug problems, don't forget to check your plug. Though this wasn't my problem.

My problem ended up being the fuel I was using. When the jug got down to about 1/3 full I started having these troubles. I swapped out to a new jug of 10% fuel and all my idle problems went away pretty much instantly.

Basically, if you've tuned the carb to death, its time to look at the other little things.

Duke