How is the relationship between the center link and the tie rods? The tie rods should be parallel with the center link when steered straight ahead. It's making me wonder if the crossmember isn't perhaps mounted too far back in the frame, causing geometry issues in the steering linkage. Specifically, excessive toe out on turns, which is usually an issue with a bent steering arm on the knuckle. But with it doing it turning both ways, about the only things it could be are the crossmember incorrectly positioned compared to the steering box/idler arm, incorrect length pitman and idler arms, or both steering arms on the knuckles are bent. I find the last one to be unlikely.
