6.0 bucking and swishing sound - after it warms up

[GSO]

I have a 2003 6.0 liter F350 - First noticed the truck was making a puffing/swishing sound as I was pulling a horse trailer up hill - let off the throttle and it went away.
This issues has become worse recently - when the engine is cold it runs perfectly, once up to running temp it starts again. The truck hesitates when accelerating and it make the puff sound - sounds like it comes from the air intake/air filter area.
Has anyone ever seen this phenomena ? Took a mechanic for a ride and he said "fuel filter" - I don't buy it because when it is cold it has full power and no hesitation.
Thanks in advance for any help.
Gary

[HAM_RADIO_MAN]

Do you have any trouble codes or performance data from the truck. ICP , IPR , Turbo performance. It may seem like some of us here have a physic connection to these trucks, but what we really need is some solid data to work with. Anything you can tell use might help us help you. Maint and repair history etc… This could be a lot of stuff. Exaust leaks robbing the turbo of power, EGR stuck open ETC ETC ETC… More info please.

Do you have any soot on the firewall?

[colinmitchell111]

my truck was bucking and turbo farting at WOT when I bought it. pulled the egr valve out and it was all sooted up. cleaned it with carb cleaner and a wire brush and she runs like a rapped ape.. this will be your cheapest/easiest bet to try first.

[J. Wheeler]

had an 03 doin the same thing along with puffing smoke, unpluged the EGR valve and it stopped. not a cure but its free and quick