Doing some tuning for a friend I have come across a problem. It is not in the tuning as I have exhausted that option. I have put a completely stock tune on it and countless other tunes that have worked well on previous customer's trucks. I know this is not a tuning issue, since a stock file does it as well, however I was hoping someone else may have ran across this problem before, and know how to tune it out. If you put the truck on cruise at around 2200 rpm, it does fine until the cruise backs off going down a hill. When cruise brings fuel back in to maintain speed it bucks and surges pretty violently. It also does it, but not nearly as bad, when regulating speed with your foot.

Now on to the truck, it is nearly stock, other than programming, 180hp injectors, arson 3 kit on the cp3 and a few other things that wouldn't really make a difference like clutch...etc.

Any help would be appreciated. I have logged the truck on every file, and you can see the rail and mm3 surge with the truck, but I cannot find what is causing it. I am starting to wonder if it could be in the FCA but have no way of confirming, as commanded DC and actual DC are staying in line.

Thanks in advance.