Hi, at first I thought I a miss, but the HB did have a little wobble to it, so I the harmonic balancer changed out for a new GM part, but the vibration was still there, So I started to think I had a bad plug or spark somehow. So I changed the plug wires to a AC Delco brand new set and some of this Miss or Vibration was removed, but I still have some kind of a vibration between 600 RPM and 1200 RPM ? and I'm out of ideas as to what it could be, also you feel it when the car is in park or neutral. The Corvette only has 21K miles on it and was well taken care of, never in a accident or other damage event, so ?