Quadrajet carb and poor miledge

[crawdad]

The best I can do with miledge is about 11 miles per gallon right now (around town) . I've got a 305 CID engine, Q-jet carb, and auto tranny. I've replaced the spark plugs, etc., and adjusted the mixture on the carb. The only problem that I can see is that the carb seems to still be running real rich. The tailpipe is black and the smell of gas is strong sometimes. However, the engine cranks, idles, and runs just fine. Doesn't skip or anything. I'm sure the carb is probably what's causing the poor miledge, but what could be wrong with it that would cause it to be running so rich and what can I do about it? Are the Q-jets fairly easy to rebuild or do I need to start looking for a good carb mechanic? Thanks for any help. (BTW, the truck is the 85 in my sig and it's all stock)