with an engine blip, it should come down to <2krpm pretty instantly. it shouldnt linger up there.
is your choke lever (on left side of carbs when sitting on bike) pressed all the way down whenyour bike is warmed up?
it may be that your slides are still too far open when you idle set screw is out all the way.
suggest setting your idle screw to touching the idle tang thingy, + 1 turn in, and then set your slides with the 1/8" drill bit. you can do this with your airbox and tank off. this will allow the slides to close hearly all the way when your idle screw is turned out.
really need to do a vac synch to get them dialed in completely.
sounds like you are getting closer, though.