I'm kind of late to the party here but if you're still chasing this problem:
I agree with most of these others that it's ice in the fuel, probably the filter. If you can get it into a warm garage, it'll thaw out in a couple of hours. If a warm garage isn't an option, a tarp that could go over the car and reach the ground and then an ELECTRIC space heater under the car near the fuel filter if possible should get it going. A hair dryer to the filter might be faster. If you don't have a tarp, putting hay or straw bales around the car to keep the heat in would work as well.
You said the tank is full, but if there was room for 5gal of room temp gas in the tank, that'd probably thaw it out and allow the HEET that you put in the tank to work.
This brutal cold just makes everything more complicated doesn't it?
