My Mountaineer is currently in the shop for the second time to try to resolve the vibration issue. There is a technical service bulletin (TSB)that seemingly recognizes the problem at http://flatratetech.com/oasis/TSB%2002-10-1.htm. My dealer did the repairs mapped out in the TSB -still didn't work. My dealer also conveniently said they thought it was fixed and didn't notice it anymore, so I went for a ride with the service manager and the mechanic together - it was too obvious for them to deny. So now they apparently are waiting for some special instrument that will isolate exactly where the vibration is coming from so they can fix it. I figure I'll go through the motions and if they try four times to fix it and can't, my states lemon law kicks in and I get a new truck. I re-drove an two identical vehicles to mine (AWD V-6)on their lot and neither of them had the problem. I even dragged my salesman into driving my vehicle and the one on their lot so he could see the difference and vouch for me.
I know exactly how you feel - I've gone on two long trips since buying the vehicle two months ago and the vibration angers me to no end. A brand new 30,000 SUV shouldn't feel like a tractor at highway speeds.