I went to Columbia today and it was the first time going on the interstate since getting my new Revos. I first got it up to 70MPH and it started vibrating, then 80 then vibrated worse, then 90 and worse again. After bout 20 mins it quit vibrating real bad and just did it a little, at all speeds. Any idea why it vibrated real bad at first, then just kinda quit vibrating?? Anything I should check out?