The thermostatic idle-up valve (AAV) is under the throttlebody and
connects to the engine cooling system thru two little rubber hoses.
If the valve is still there (nor removed or blocked off) then both of
the rubber hoses should get hot as the engine warms up. If only one
gets a bit warm and the other one stays cool, then you need to take
a look at the idle-up valve. Best way is to remove the throttlebody
and then unscrew the valve for cleaning or replacement.

If you don't have an idle-up valve or it has been blocked, just raise the
cold idle a bit to say 800rpm using the air bypass screw down the tube
on the side of the throttlebody.
Cheers... jondee86