Third year in a row as soon as the temperature drops my truck starts smoking a greyish / white smoke.. Seems to be when I am under 2k rpm but while accelerating. Happens even when I am not hauling. Have had it in the shop at least 6 times since I bought it new. Really starting to annoy me that they cant figure out what is causing it. I'm not talking a little bit of smoke here either!!!!! Enough to cause traffic to stop. Also fuel mileage has went from 14-16mpg this past summer to 10 -11.5mpg in the past couple months. Any ideas??????