I have a 2011 F350 6.7 with 41,000 miles on it. Its all stock mechanically and lately, at start up theres a strong smell that the truck has never had. Can't quite pinpoint what it smells like but its strong. Also for a brief period after shutting the truck off the smell arises again. I think it's coming from the exhaust. I had my dealer check it out and they couldn't find anything and they said leave it here for a cold start but its tough to do here in New England in the winter since I plow. Also, it has happened 3 times now but not in a row, ramdomly at cold startups, the truck doesnt want to turn over and seems like it almost dies before finally starting. Don't know if this is related or not. Any help would be appreciated. Thank you.