Ok, a while back I had some nasty vibration coming up through my tank. I found the culprit, it was loose tank mounts in the back. I took the tank off, put some loctite on, and the vibration went away. Now I have the vibration back. I took the the plugs out to check them. I thought that the front one looked a little black, but the rear plug looked great. Would a fouled plug cause this vibration, or do you think that I need to take the tank off again and check the tank mounts?