Steering rack problem - steering tight?

My car's steering is tight when turning to the right. This is especially noticeable during the first 90 degrees or so of turning the steering wheel to the right. The problem started when I noticed that my car was pulling a bit to the left when driving around 70+ mph. I took it to Sears for an alignment. They told me that my wheels were a bit out of alignment and they fixed the problem. I took it back on the highway and had the same problem. So, I took it back to them, and they worked on the car some more. I have no idea what they did, but after the second visit to Sears, my steering wheel feels tighter when I turn it to the right than when I turn it to the left. After I turn the steering wheel to the right, it springs back to the center quickly while driving. When I turn it to the left, it feels softer, and stays turned a bit to the left until I manually turn it back to the center. Before I took the car to Sears, both sides felt even. I recently took my car to an Acura dealership where I was told that the problem could be that I had a rack that needs to be replaced?