I changed the fuel lines back, from 2mm to the original 2.5 mm. The midrange is running a little better now but not like it should, its missing about half the time its running in the midrange.
As for the post from "rcman", yes, it would be strange that its lean on midrange but not in the high range.
I tend not to believe its related to the "common 91 FX needle valve problem" as it doesnt deadstick or show the caractaristics of the other posts related to the o ring problem, but I may be wrong.

Another factor involved is that the feed line goes from the tank then down a couple inches to a GP fueler valve then back up to the needle valve. The middle of the fuel tank is located 1/4 inch above the spraybar.
Hope this sheds some light on any ideas you may have.