Originally Posted by mudrunninpig
check your FICM voltage
Sorry, I didn't mean to hijack earlier... FICM might be the problem, or injectors... You really need to have the truck scanned by Ford IDS software or at least autoenginuity software to properly diagnose. Without hooking it up and seeing it on the computer you're flying blind. Internet diagnosis can tell you what it might possibly be, but until you have it checked all you can do is throw parts at it, and that's the worst thing you can do with a sick 6.0L. You'll waste more money chasing theories by far then you would have if you just pay someone $100 to check it out right. Find out what faults and codes the truck has and get back with us. Much easier to diagnose when the right facts are presented.