Any further info on this problem?? I have the same symptoms... I have used a data capture tool to determine that my ICP pressure sits at almost zero for about 3.5 seconds, then jumps up rapidly and the truck starts. After running for a minute it will restart quickly... but if the truck sits for 5-6 hours it will crank 3-4 seconds again before building ICP high enough to start.

I suspect a HPO leak somewhere that allows drain back after sitting for a while, then it takes a few seconds to purge/compress the air in the system before building enough pressure to start.

(My truck is an 07 F350)