if it ran ok when last parked 2 years ago what would cause the carburetor screws to go out of adjustment? and is 2 years of inactivity enough to mess up a carburetor that was otherwise ok?
They don't go out of adjustment. Gasoline in the carb evaporates and leaves solid deposits called varnish and other solids. By opening the idle screws as Carb King suggests these deposits might be, can be, hopefully will be sucked out. The idle circuits will then be clean and the adjustment returned to normal.
FWIW rubber products, Gaskets, seals and the like tend to dry out and crack rot shrink flake off and leak over time. Six months siting inactive can cause all of the above and more.

Tim White

49 Chevy panel
91 Jeep YJ