I have been having similar problems in cold weather.
I changed the PCV and some of its associated vacuum tubes, and that seemed to have improved the problem but did not fix it.
I am starting to suspect the IAC, but would like to know if there are any tests that I could perform on the IAC before taking it off.
Buried inside this thread is a lot of information on the IAC, and IAC cleaning including a photo, but would like
to hear if anyone has a test for the IAC.
IAC Thread