I think your EGR is cycling too much, if they touched anything in regards to the EBP sensor this is most likely the cause, mine was doing this even at idle and it caused my Exhaust brake to fail and all the pressure would go through the CAC. Ford is supposed to have a new program that they...
I think this problem is fixed (for now) I brought it to my local BD Performance for a check up on the BD brake (as the Ford tech nuts tampered with it) and it turns out that one of the recalls done was to the Exhaust Back Pressure sensor and after it was installed, it was not calibrated...
I had it done too, totally screwed up my BD Exhaust brake Auto-Loc down shift parameters, sometimes I have to manually shift it, and it really sucks fuel when pulling, but it does have more HP and torque, so I'm neutral.
I am noticing when I am at 1400-2000 rpm cruising along the engine sounds like the throttle is constantly bumping up and down and when I idle it, the turbo whine is extremely noticeable and the waste gate noise is louder when there is very little boost. At lower speeds, the truck will actually...
My '05 F-450 has a BD Exhaust Brake http://www.bd-power.com/ford/product.php?pn=Exhaust%20Brakes&tt=ford installed in Oct '05 and I was warned to remove it last July after the tech people already told me the the 6.0 has excellent compression hold back after 3000 rpm (B.S.!!) and if I didn't...