If the midrange is much too rich, then it's likely the idle's much too rich. Too many times, a very low idle is achieved, but the midrange is not right. You may have to give up some idle RPM to get a good midrange setting. Any idle below 2,500 RPM is considered good.

Rotating the spraybar actually tends to richen the midrange, but you then have to reset both the high-speed and idle needles. You want the idle needle as lean as possible, yet still giving you a good midrange. The mid will still be slightly rich, but that's OK, you won't have the severe hesitation.

The engine will take a set more easily once it's had 2+ gallons' worth of fuel run through it.