I would take a look at the VSS. The cruise is meant to cut off when you drop a certain amount of speed as a safety to not damage anything on the drive train forcing it to go when slowing down. So its seeing the speedometer bouncing as the truck quickly changing speeds.
96 300ci M5OD 2wd Reg Cab Long Bed 3.31 LS Gears and 8-Track player
A question that sometimes drives me hazy: am I or are the others crazy?