My 88 wrangler has a strange vibration. I can't quite figure it out. Here's what it does: I had it on the highway yesterday and once I got up to around 65 I could feel a vibration in the floor by my feet, and I could also feel it in the steering wheel, so I assumed one of my front tires was out of balance or something. Then I was driving along, and with no change of speed(or anything else for that matter) the vibration stopped. I had about an hour drive, and the whole time it would start and stop for no apparent reason. Anyone have any ideas on what this could possibly be, because I am really stumped.