Your truck should still be under warranty. Have you changed fuel filters lately? Gelled fuel is one problem, a P2290 injection low pressure has nothing to do with fuel, sub temps ( unless you live in Alaska ) the truck does not have to be plugged in to start. In cold weather it is nice to plug the truck in for an easy start, once warm and within operating conditions, a no start is usually the high pressure pump connection. In my opinion with out seeing the truck and because of an early build 06 your HP pump snap to connect fitting is leaking.
Here is a link to the 2003 6.0L Bible (
Click Here) that you can look over. The HP pump is in the same position on your 06, updates have been made through the model years.
TSB 06-14-6 Applies to the HP branch tube or snap to connect fitting. A technician has the tools to properly diagnose the engine. To speculate as we have here and start disassembling the truck is not the way to go. I have given you an idea as to what might be wrong.