Another cold no-start fix. Simple!
Buddy of mine has a 03 6.0 and it had the hardest time starting only when cold. It wasn't stiction as it just plain wouldn't start. It would start all day long when it was warm. We changed his oil to the T5 and it didn't really help. He was getting VERY frustrated and it just seemed weird. We never checked the FICM or glow plugs.
During all of these failures to start with it cold, he killed his batteries. It got to the point where he would try 3 times and then it would be dead.
We replaced both batteries. Both failed the test.
His truck starts every time now.
So to those of you with a no start condition only when cold, check your batteries.