I live 2 miles in on a dirt road and I make this 4 mile round trip 3 or 4 times per day. I specifically bought this truck to once and for all insure a smooth ride over the various bumps, holes, washes, etc. I've driven everything from sedans to duallys to luxury SUVs over this road and NOTHING gives me a smoother and more importantly, solid ride than my Raptor. I can drive this road at 25mph or 85mph, it really makes no difference. My stomach may "bottom-out" in anticipation of an approaching wash but the truck handle it without a problem.
I had the truck serviced a couple months ago and afterwards the truck rode so rough when I drove it over this same dirt road that I published the problem on this forum. Someone mentioned tire pressure so I checked and sure enough, it was way high. I adjusted the pressure and I was back to the comfortable ride.
It's just a fantastic, very capable truck in all ways. I'm sure there is a simple explanation of the problem you encountered on the test drive.