Hi. I have a 99 Blazer. When I drive it over 20 miles I start to feel and hear a vibration only when turning slowly. I have changed all four control arms, new wheel hubs with timken bearings, all ball joints, steering box, tie rods, pitman and idler arms. The vibration once warm was there even before all that work. Again, it only happens when turning slow in either direction. I really can't tell if it's coming from the front or rear. Any ideas? Thanks!