What is causing my 2006 kia sedona to vibrate severly at 60 to 70 mph? Have changed tires, rotors, brakes, and 4wheel alignment.

...see your tire shop, your tires are out of balance, and should be rotated anyways-

either they did not do a good job of it, or they did not spot a loose bearing, or weren't lookin' most assuredly took a look at your tie rods and control arms for excessive play? Go to a different shop, one who is owned by an old guy who smokes a pipe.

a misfit driveshaft or center bearing if equipped will, shake shaft up and down..raise each wheel .spin by hand look for a wave in rim or up and down tire movement. even a bent hub bearing will wave ,a tire mounted with a button of rust under the flange will torque down cockeyed . you can try this only if all the old guys smoking their pipes are dazed and confused ,it is the weekend you know!

I have a 2002 Sedona and it was motor mounts.