The dealer's service dept. can't figure out what's wrong because this doesn't happen during their test.
Our 2003 Sedona van (with about 97,000 miles on it) is usually fine. However, after about 30 minutes of driving at highway speeds, the van starts shaking severely. If you let up on the gas pedal and coast, the shaking stops. If you try to maintain speed or accelerate, the whole van shakes terribly. If you hit a bump in the road, the shaking stops for a second, then resumes. It does this for about 15 minutes, then the shaking suddenly stops and all is fine again. It's gradually getting worse and happening more often and at slower speeds. They claim it's safe to drive.
I'm the original owner, so the 100K mile powertrain warranty is still in effect. Over time, the dealer has replaced 3 axels, some lug bolts, and a motor mount, and still can't determine what's wrong. It's not the tires because the shaking would be all the time, not just when accelerating.
Any of this sound familiar to anyone? Any suggestions? Thanks.
(This site is a great resource. Keep up the good work.)