Under the coach and I've seen this before but never sure what it is. Drivers side, before the hydraulic lift pump.
On the other side of the plastic cap/end is a metal housing with fins. One of the tubes leaving it goes to the below breather tube picture. No big wires going to it. Looks to be an emissions thing maybe? I didn't try too hard to trace tubes coming from it. Just curious if anyone knows. Looks to be a Ford thing.