I think you're saying, with engine on [vacuum] your halfshaft spins with the wheel. When truck is off [no vacuum], your half shafts spin with the wheel.
That's telling me, either you don't have vacuum at the hub pulling the IWE to disengage, OR, there is something wrong with the IWE, jammed in or something.
First thing would be to see if you have vacuum at the IWE. Leaking seal, hose off, or cracked.
At idle speed you'd have max vacuum off the engine, so let's see if you have vacuum at the hubs. You could pull the hose off and see if you've got a good suck on it, but that isn't gonna check for a bad seal, you'll need a vacuum pump for that.
Don't think there's anything wrong with the Tcase, it sounds like it's doing what it would.

 

When I left work last night the first couple times turning left I heard this awful scrapping sound i'm guessing this is what my sound was?It then went away and didn't hear it for a good 20 miles the rest of the way home I think I might have heard it 1 other time driving straight but not sure.My question is does the noise usually come and go like it did for me,Thanks

 

I wonder if this is what you experienced? Read post # 156 > https://www.f150forum.com/f118/repai...6/#post5210614

 

Yes, the noise is intermittent, that is why some dealers, along with lack of understanding, turn many owners away when the dealer can't replicate.

I'd betcha that's exactly what happened.

Regardless, the grinding shouldn't be happening. My '17 did that with less than 500 miles on it. Had to educate myself how the system worked, and traced the problem to the checkvalve. Replaced it and 8500 miles later, no problem.
Others here have done the same with good luck as well.
Since the weather is turning cooler now, I suspect there will be more and more mention of this.
Ford has finally come out with a TSB on this, I don't have the number, and an updated hose/checkvalve assembly.
A YG360 valve also works, it has a slightly larger fitting on one end, but that's what is in mine

Ford updated assembly https://www.tascaparts.com/oem-parts...ube-fl3z3a788a

 

TSB 18-2273

I explained my symptoms to my dealer and told them about this TSB and they did it without any hesitation. Here is attached TSB

TSB 18-2273

 

Thanks Mark, that's the one.