X2 for the IAC -- They can freeze in place at times - the air-speed through there coupled with the shaping of the ait passage can lead to some significant icing.
If you have time to remove it and clean it -- a little coating of WD40 helps to keep the moisture build-up from being able to "stick" as well... (I use SeaFoam's "Deep Creep" product on them) - stay away from anything with silicones in it -- the silicone's can 'cloud' your o2 sensors. (so no furniture polish or baking sprays
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