my .02 what you experienced is prolly normal. i try to keep mine on 1000 rpms for a minute or so after a cold start (below 32deg F).
i would be more concerned if what you describe was happening after full warmup - and full meaning more that 1/2 hour driving at these freezing temps.
agree to replace those filters so you will have a baseline to go by, if there were no records when it was done last.
good luck with the new wheels.
