Prefer holleys also. I just think his problem is a simple matter of cable or linkage adjustment. Would explain why it's ok till it warms up. The tight throttle plates are cutting of air which is what you want on a cold engine, less air more fuel.
For the sake of us who are not color blind. If you going to do two tone the green with a grey or silver. Plum crazy and green , you may as well paint every panel a different color. Personally I would stick with one color.