My 2003 Avalanche check engine light comes on and goes off. Truck does not like the cold weather period ! I replaced the cats in the summer of 2007 with 55k. It was covered thank god. I thought maybe that was the problem back then. About a month ago that check engine light came on again and some days goes off. I do get a rough idle on cold mornings. Once truck is warmed up it is fine. Just drives me crazy !
Help !