It sounds like you have a fairly good vacuum leak.
Places to check are the obvious, intake gaskets, carb gaskets as well as making sure unused bibs on the carb proper are sealed off. Especially so the small ones at the front of the carb. (Passenger side bib is ported vacuum and drivers side is full-time vacuum.)

Do you have another carb you could try?
That would duplicate the overly lean condition if it's not a carb problem.

You may want to take at look at Edelbrock's online carb manual.
Go here: http://www.edelbrock.com/automotive/...ubleshoot.html

Backtrack from there to access other areas of the manual.