Weird deceleration problem

[Jaredpear]

When on the highway cruising and I let off the gas, after about 5 seconds, the trucks fuel trims and timing goes to zero and my rpms start dropping and speed start dropping fast, almost as if the truck is engine braking.

 

[Jay33089]

I accidentally left a o2 sensor unplugged one time. Did something similar but also surged at stoplights!