My father in law has a 2005 SR5 V6, the steering is acting really weird and I was hoping that someone can point me in the right direction.

Story:
Steering was very tight 2 weeks ago, he took it to the shop, the shop replaced the lower u-joint in the steering which connects the column to the rack. Now, the steering feels very loose (the only car I've ever driven with steering this loose was my dads 93 towncar ) and when you make a turn, it kicks back in the other direction a few times. It even does this if the car is not moving, for instance....in a parking spot- if I turn the wheel to the right, it will kick back to the left 1-3 times in a row.....

I have a 2005 100 series, and I drove a 1998 t4r for years before the LC..I've never felt anything like this- seems really dangerous. The PS fluid is full and looks good. The truck is really rusty, but does not seem structural imo..

Thanks in advance for any help!