Howdy! Got kindof a weird problem. I have an '06 6.0 and had the Turbo "rebuilt" by a ford dealership. It had an under boost code and had no boost towing 7K up hill. That was done 2k ago. I don't drive the truck much but when I do I'm towing. Earlier this summer I was towing my trailer(7K lbs) back fron colorado and I had it in Tow mode I tapped the brakes going down hill and the engine decelerated, the trans shifted to a lower gear about 2200rpms and heard a slight rattle noise. I have never heard that noise before, and this was the first time I towed a distance since the turbo was rebuilt. The symptoms are hot weather, after towing about 200 miles, and on deceleration, although I hear it slightly when I will slowly accelerate after the decel. It was making the rattle again this weekend at the same place it occured earlier this summer. I have towed the same weight on shorter trips and it wont make the noise. Any suggestions....Oh and there are no codes just a slight rattle noise.