When I turn a corner in my 1999 Silverado 4x4 2500, automatic, it feel like something heavy is attached to the back of the bed which tries to pull the truck off the road. The pickup has 205k miles, and has had the steering gear and idler arm replaced in the last two years. The tie rods have no slop, and I cannot move the front tires much with both off the ground. I find nothing loose at all. This problem developed suddenly, or at least I think it did.