Small Engines (Lawn Mowers, etc.): Craftsman LT 1000, screw adjustment, model numbers

Question
I have a Craftsman LT 1000. When I turn it on, it idles very roughly and
louder than normal. The engine idle goes up and down. Before I bought it,
the previous owner replaced the fuel filter and spark plug. After this was
done, the engine idle still goes up and down. The previous owner also stated
that the mower has been stored away for awhile.  Is this repair a simple idle
screw adjustment or do you think there is something else wrong?

Answer
Probably has some moisture or crud in the carb, for me to go into
much more detail than that, if you could find the model numbers off of the engine, I could be more specific.
In many cases removing the bowl off of the carb is not too difficult,
and a quick cleaning will cure the problem.