Also, check to make sure that your carb bolts are tight.... I've had that one burn me before... waste all day looking for problems, when the obvious one was that the carb was loose. You may also look into getting a new gasket for it.
Easy check for vacuum leaks.
With the engine running, take some carb cleaner, and spray around the manifold to head gasket surfaces, the Vacuum tree on the manifold, and around the carburetor. Any leaks in these areas will cause the engine rpm to drop, and if it does, then you have found your vacuum leak...or at least one of them.
Is this a california emissions car? If so, and your emissions stuff is still attatched, that may be the source of your problems as well....
~THOR~