On my 99 Vortec Suburban, I added a tube from the radiator support to the stock air box cover. It seems to work great during the summer, and when towing.

The other day, when it was 16, even after my truck warmed up, it would idle at around 1000rpm. I swapped out the cover to the sealed spare, and it went back down to the normal 700ish.

I was just curious if any of you with the production CAI's have experienced this.