I would think your leaking carb gasket is part of the problem.
That series carb also has a diaphram under the rectangular cover on the side of the tube that harden over time. Both the mounting gasket and the diaphram are included in the Briggs Carb Rebuild Kit
Part Number 494624. The kit lists for $12.55 on Briggs Parts Site, and should be available at your local Briggs and Stratton dealer.
Rick
November 2005