I reposted mine because there's a reason I asked it. I believe the geometry is incorrect. Your post on #1888 got it, it has to come out to a 1 to 1 ratio. If you adjust it to full travel at wide open and have slack back on idle you need to correct the geometry. It could be as simple as drilling a hole or moving it at the carb. It could be difficult as fabricating a longer level but I'll bet just drilling a hole or moving it will solve your problem.