Recently I have been experiencing a wierd "chugging", lets call it at start up. A lot of white smoke and chugging and then goes away after "wait to start" light cycles a few more times. Is this signs of injectors failing? Truck has 125k on clock with what I think is orginal injectors. No other problems and drivability is fine after. Well there is ono other problem it seems to have decreased fuel mileage lately, does cooler weather cause increased fuel delievery like 'fuelly' cars.?