2007 Honda Odyssey Engine Shaking?

Recently I've noticed that my van is shaking really bad, then it just stops. It does it at 25 MPH all the way up to 70MPH so I don't think speed is a factor. It hasn't done it enough to determine if it's on acceleration or deceleration, but I would say I mostly notice it at idle or cruising speed. It does do it at a particular location of my commute but again I dont think it has anything to do with terrain or speed. If I were have to make an educated guess I would say it does it on acceleration. It will almost violently shake from the front end and then 3 seconds later it just stops. It doesnt seem like a tire or rim problem because I've had those before and know what they feel like. Also, it's a front to back shake as opposed to a side to side shake. Kind of feels like your driving over 30 or so mini speed bumps. My car is fairly new with fairly low miles so I wouldnt suspect a transmission problem but who knows. Also the other day I stopped at a stop sign then when I went to start going again it felt like the transmission was in nuetral, I even checked to make sure I was in drive, but by the time I looked down and checked then looked back up again it started going, this seems odd to me as well, seeing as though I was in drive when I came to the stop sign and never shifted out of drive, yet it felt like it was in nuetral. Any ideas? I don't know if the problems are even related as it's only done the nuetral thing once but it shakes randomly all the time.