A dirty throttle body is not likely to cause poor idling but it would not
hurt to clean it.  Remove the black plastic snorkel that leads to the engine
air filter and spray the inside of the throttle body with carburetor cleaner
or throttle body cleaner and wipe with a clean paper towel.  Rotate the bell
crank that the throttle cable is attached to so that the butterfly plate
inside the throttle body is open and spray and wipe again.  Also spray where
the pivot rod for the butterfly plate passes through the throttle body.  The
engine will probably smoke and run very badly until all of the residue from
the carb cleaner is burned off.

Check the engine air filter to make sure it is not dirty.  If you look
through the air filter at a light, you should be able to see the light
clearly.  If the light is dim, replace the air filter.

Check the black plastic tubing between the air filter and the throttle body
for holes or cracks.  If you find a hole or crack, seal it with duct tape.

Check the idle air control valve (IAC) on the throttle body.  If it appears
to have a gummy residue, clean it with carb cleaner or throttle body
cleaner.

If that doesn't work, check the MAF sensor on the engine air filter housing.
There is a tube that protrudes from the MAF sensor into the air flowing out
of the air filter housing.  Clean the fine wire inside the tube with
carburetor cleaner, making sure not to damage the wire.