I also have the Lil MB motor in my truck with the intake heater.
I find it hard to believe that 19 degrees is cold enough to stop a modern diesel eng from rolling over and firing..Just doesnt seem cold enough from my experience of playing with trucks..But then again there is alot I dont know about the newer equipt out here.
I wonder if its not due to loss of prime, (not knowing how long it sat) to much corn oil in your pilot fuel ,,slow cranking speed???I'm just thinking it may and or could be something else causing it to start hard while cold..