I don't have a lot of time this morning, but I'm very suspicious of your idle vacuum. How carefully have you checked for vacuum leaks? The problem you have sounds like a fundamental one, not one that you're going to "tune" out of it. That carb should be close enough out of the box to run smoothly and provid eplenty of power, but I go back to the idle vacuum. That's a good indicator of something wrong. Try and backtrack through the changes you've made since it last ran best, and go through a process of elimination.
Just my .02
Edited to add...checking the timing on your cam might be a good idea.