I had a similar problem making a tight U turn. Bad tie rod in my case. Check tire pressure, and re-torque the wheels, then jack up the front end and check it. You can also have a friend turn the steering wheel from lock to lock, with the car on the ground. Look under the car and observe all the steering linkage. It is pretty easy to see a bad steering part that way. As the bad joint comes under load it will have abnormal movement to it. HTH
You can also rotate the tires front to rear and see if the wobble goes away, or changes any. In that case its a tire problem.