Surging during idle...

Nano,
I was having MAJOR idle issues with my truck. Had injector cups and orings done. Replaced cam gear and bull gear, new damper on crank, new injector harness, ran overhead twice. It still never went away and I can now attribute it to the egr/regen system and here is why.
Long story short my MCM went out causing a no start issue and throwing a communication code to the vgt/vpod. Dealership checked all wiring and then put in a known good computer which fixed the problem. Flashed it and gave me back a truck that doesn't hesitate or lope at idle.....UNLESS it is in the middle of a regen and cooling down when coming off the highway and it's nowhere near as bad as it was when it did it before. It will hiccup every now and then like a couple times a week compared to every time i was at idle before. I drive manhattan everyday so I spend a lot of time at idle going light to light so I can definitely see a difference.
Have your ECM/MCM checked out. Not cheap but could solve your issue.