Surging off idle while coasting in N or clutch in

[quicksilvr]

New guy here with a very strange issue I've been trying to track down. While coasting to a stop my truck surges from idle to 900 or so, this is with the clutch depressed or in neutral, also only while brake peddle is depressed.

I know these trucks are programed to idle up while coasting without brakes applied to about 900, my truck does this correctly and will not start surging until I depress the brake peddle. Eventually once slow enough or stopped the surge stops. It's not a violent surge, just smooth idle up and down and it has me completely stumped.

**my truck is an '05 NV5600 w/ 35k miles**

Thanks,
Eric

 

[SuperiorRam]

Clutch not fully disengaging ?

 

[quicksilvr]

It's definitely disengaging, it's got to be electronic related. Figured I'd see if anyone on here has seen this happen.