Hesitation after decelerating, rattling noise and smoke.

[Grasshopper2Ant]

I have a 2.5 TB. When I decelerate then press the gas pedal I hear a rattling noise under the hood and the truck slows and puffs out smoke when I press gas and when it clears its's throat it goes again.

Sorry for the vague description, but that is the best I can describe it.

EGR Valve
Fuel Pump Seal
These are some of the causes I found on this forum. Is there ways to test and narrow the problem or any one else have this problem before?

[LeeHammy]

Well for starters.. Remove your EGR. Simple to do. Nothing negative without it, you'll still pass air care, you get more HP, and you don't throw extra heat and crap into your intake.
The hesitation could be your wategate. When they get old they can become sticky, ie open or closed, no range. It should slowly open to maintain boost. You could be hitting boost then it slams open you take your foot off the gas and it takes a while to close so when you hit the peddle again your bypassing your turbo and getting little or no boost. Your waste gate can be checked by getting a hand pump. Connecting it to your waste gate boost hose and slowly adding pressure to watch it actuate. If its not operating normally it will be clear. But don't add any more than 12psi to be safe.

Those are my thoughts... Feel free to correct me people.

[tonydca]

What colour is the smoke? White (unburned fuel) or black (partially burned fuel) or blue (engine oil)?

[Grasshopper2Ant]

Thanks for the replies guys. I will look into the egr first.
Also, the smoke is gray, sometimes black.