I'm guessing you meant valve cover gasket, not head gasket. I find it hard to believe that adding 10 gallons to the tank caused the truck to magically start. Try and repeat the results to be sure. Make sure the start did not happen because it was later in the day and warmer, the engine had been cranked enough to warm things up a little, etc.

If it's a fuel tank level issue, then your fuel filter bowl should be empty after a couple of cranking attempts with a low tank. This of course would be the cheapest and easiest thing to fix, which also makes it less likely if your luck is like mine.

What are you using to pull the codes? Can you monitor any live data? Does the truck start any better if you unplug the ICP sensor?