hmmm … well, first thing, check the power steering fluid level, check the PS belt tension, and that the power steering pump is actually turning when the engine is idling. The PS pump provised powered-assistance to the steering rack, and the tie rods provide a mechanical connection from the steering rack to the wheel hub (or knuckle) ass’y, pushing or pulling on it to turn the wheel. The tie rod connections have moveable joints, sort of like a trailer hitch works. If the tie rod lengths were incorrect or the wrong parts were used for the joint connections, this could happen. Seem unlikely, but should at least be considered. If I had this problem myself, first thing I’d have a helper drive the car slowly on a level surface and turn the wheels one way and another while I walked alongside looking for something unusual in the way the wheels moved. If I couldn’t spot anything, I’d remove the tie rods and have a look-see on the bench.
I think you’d get better results using an inde shop rather than a chain for this type of work. Suggest to use an inde shop next, if the rack indeed does need replacement.