1. THe black cap on the choke is adjustable. 3 screws. Turn it slightly to the lean side. Spray the mechanism with some carb cleaner too.
2. Bog at upper rpm could be fuel pump not supplying enough fuel to the carb.
3. Might be accelerator pump needs adjusting or secondary air valve is set too loose.
Some links for you!
Study them closely. There will be a test. LOL!!!
Quadrajet Info by Lars - Corvette Forum : DigitalCorvettes.com Corvette Forums