I have a 2005 F150 FX4, this just started since it got cold. It has a vibration you can feel all through the floor, if you click it into 4WD it smooths right out.
Any ideas?

 

If you also have a noise coming from the front, either or both sides, it could be a bad solenoid/IWE.

 

They replaced the right front HUB and the vibration didn't go away, I am waiting on a phone call right now

 

Any update on this?

 

Have you checked the vacuum connections on the tops of your hubs? Mine did this awhile back and it ended up being that one of them came off and that one hub was locked, causing it to vibrate like crazy. After plugging it back in al of the vibration went away. It is a 2 in 1 hose that is ran to the top of the hub, which is behind the brake in plain sight.