OK, some answers...

The high limit screw was so far out I actually removed it from the derailleur, so its not that.

I'm betting that the preset click positions on the shifter arent far enough apart. There just seems to be not enough throw between clicks for it to properly shift and stay far enough outboard. Sure, it will travel far enough, but it wont lock into the outer ring position. On my 105 9-speed setup the front throw is the same, but the FD arm travels about twice as far.

I'll get a Sora or Tiagra FD and bolt it on and try, but I'd like to bet that fixes my problem.

Jim