[Oh boy]

I have a 97' grand voyager rallye 3.3 and had the same problem at 144,000 miles. I had a monkey mechanic drive it and was told it was the transmission. I took it to a "trusted mechanic" who drove it around the block and told me he knew what it was. After a couple hours he called me up to tell me that the flywheel was cracked. $450.00 later the vibrations and noises were gone. I don't know that you have the same problem but you may want to check that.