Looking at a 97 dolphin, current owner has put all new batteries in it and is having new brakes and lines put on has all new tires, and all systems works great. Problem I need help with is that when we took it down the interstate for test run it had a slight vibration, or shimmy, not bad at all, but he said it didn't do that last time he drove. Was wondering since it has brand new tires all around if one could have a flat spot from sitting? Or could it be something worse, like a u-joint or something. Hope someone can give me some help pretty quick thanks.