Your problem is you need a reflash to remove the limitations set by the ECU.

 

plugs were replaced and gapped properly, and im running a utec tuned by cft, I have only had this problem in the last few weeks since it has gotten cold.

 

Replaced the plugs and everything seems to be fine. I gapped them to .25 as per Dave B.

 

I had a similar problem, I ended up taking it to the dealer (without my xede or anyother mods), where they reflashed it with their stuff. It ended up fixing the problem, the dealer told me they didnt know why it happened but after they reflashed/reset everything the car ran like it use to.