theres a funny whoomp whoomp noise kinda like an air comp, when I shut the truck off. only when the truck is idle at about 11 or 1200 rpm. truck has about 1100 miles on it

 

Possible the truck in is regen. If it's idling at 1100 - 1200 RPM when you shut it off, try puting your foot on the brake. If the RPM comes back down, it's in regen, and this is normal.

 

Could also be the air from the turbo spinning faster backing up into the intake after having no where to go. The 6.0 did that and the 7.3's did too. The air rushing in suddenly is no longer needed so it makes a flapping noise. Less pronounced on the 6.4. Sounds normal...