steering rack

I have a 2002 4 runner that I purchase new, I have 260.000 miles and it still runners great, have always tried to keep up on maintenance. I recently had new front struts and upper and lower ball joins replaced.
Afterwards the steering was harder to turn and the steering wheel does not come back to center you have to turn it back. I took it back to where I had it done and they, which was highly recommended, said give it a while and should loosen up. It never did and now the shop has turned into a Jiffy Lube.
I purchase ball joints from Rock Auto, is it possible the ball joints are bad or steering rack needs to be replaced?
Have put 6,000 miles on it since done, goes down highway find, drive 75 to 80miles hour, it's around town that's a problem.
Any suggestions would greatly appreciated.

 

It may not be bad idea to change power steering fluid. I try to change mine every 75000 miles or so. It may help.