I wish I knew a plugin that did this, but what I am suggesting is that there be a program that every 15 minutes people afk for over 10 minutes be insta-kicked and the top 3 other afk people be kicked, unless they have been afk for less than 5 minutes. AFK:Not moving, not doing something, (1 axe-swing every minute is obviously afk). My idea is kind of complicated, but it would be great to have.
This idea has already been brought up not too long ago here "http://ecocitycraft.com/forum/threa...le-who-stand-for-8-minutes.32597/#post-147694" This is a great reason as to why this idea didn't generate much support from the last time it was suggested.
Essentials has an auto AFK kick feature. I'm guessing the reason you want this feature is because you can't access the server when it's full?