Check your fuel filter too. Whenyoupullitoff, you should be able to blow through it.
Lay some old sheets or tarps under your truck at night, the earlier the better. Many thin layers is better than one thick one. A tarp, an electric blanket and a bunch of sheets would be ideal. Car covers help. You can probably trap enough heat from the sun and earth during the day and from your truck cooling off at night and radiate it throughout the night to help with freezing cold starts - at least long enough to shut your truck off, let it cool down to ambient temps and trying to start ot back up. That Should tell you if its just the weather or a failing part.