Need some ideas on excessive lag

[StainlessRRA]

I'm not a powerstroke guy so I need some help! My buddy has a 06 that has gotten VERY laggy lately. The truck is stock, and will stay that way for warrenty reasons.

Anyways, he thought something didn't seem right so the truck was sent in and the turbo was cleaned out. Sure enough the vanes were sticking. After this the truck still didn't seem right. It went back to the dealer and a few injectors were replaced. Still, shes laggy. Towing a 1500lb trailer he had to keep his foot on the floor in 4x4 low in order to get enough boost to climb a hill. So once again the truck went back to ford and a "fuel pressure spring?" was replaced. That helped quite a bit, but shes still not where she needs to be. Any ideas of what I should look for? Theres a small exhaust leak on the manifold, thats getting fixed next.

Just to give you an idea of how bad it is we pointed the truck uphill on a gravel road, then floored it with zero boost. It took 32 seconds before she built enough boost to break the tires loose.(This was before the spring was replaced.) I'll try to get some video soon.

 

[strokin6L]

fuel filters replaced? What's the fuel pressure? Boost leak somewhere? Check all turbo/intercooler hoses and make sure they are clean of oil and make sure that there aren't any rips or cracks in them where boost can leak out.

 

[StainlessRRA]

I'll check all of that, she seems to be more responsive cold than warm. Once she spools up she runs great. I'm really thinking its a fuel issue.

Thanks for the ideas!

 

[UNBROKEN]

Any black smoke while it's trying to spool ?
If so....start Looking for exhaust and boost leaks.
If not....start looking at fuel issues.