2006 Sonata GL

My Sonata has a back and forth body sway between 15 to 30 mph that feels like a bent wheel or tire that has the belt separating. Had all that checked, replaced both front drive axles, replaced all four tires, balanced tires and wheels, had bearing checked, runout checked with dial indicators, front end alignment, replaced brakes pads all the way around, put new rotors on the front and sway bar links on the front. Non of this seemed to help. It seems to be in the body and not in the steering however there is a little****** motion on return to center of the steering wheel but once the car straightens out the******** goes away. After about 30mph the side to side sway goes away and you can let go of the steering wheel and it goes straight on down the road. Any ideas? Thanks