I have an 06 F-250 6.0 automatic trans. Lately i've been experiencing low power and poor fuel milage. Took it to dealer and they said they could not find any problems. No codes are present. The truck wont hardly hold overdrive up hill pulling a 16ft jon boat. I told them I suspected the veins in the turbo were sticking but they said without any codes they could not do anything about it. Not sure if they even checked the turbo or not. Fuel filters were also just changed. Below 2000rpm the truck will only make 10psi of boost.Top end still feels pretty strong. Any suggestions?