I have an 05 with about 25xxx miles, here in Alberta Canada it gets F'n cold. Anyways it was about -30 C with windchill last night, this morning I went to start it and it started up fairly easily ( which surprised me!) but it was revving like crazy and was revving up to 3K RPMs, then down to 1, then back up to 3..it did this for about 3-4 minutes until It warmed up, It seems obvious that this would have to do with the extreme cold but just wanted to see if this is a sign of a problem developing. Sometimes when the car is warmed up fully and its idling at about 900 RPM it feels like it stumbles for a quick second like its going to stall out then it goes back to idling normally.
Just wanted to see what you all thought,
Thanks!!

 

Here already a thread about it.

https://www.rx8club.com/rx-8-discussion-3/starting-car-24-c-sharing-experiece-208136/