Steering Problems In My Lumina

OK, well I have a 98 Lumina and I am having a problem with my steering. Now here is that happens, If I come to a stop and I make a right hand turn and go down the road my car will stray to the right. Now if I make another stop and I make a left turn my car will go straight. I have taken my car into Sears twice. The first time they said I needed and alignment. So the first time they did it was way off. Now After about 30 minutes of driving I noticed the same thing. So I took it back a week later and I told them what was happening, they said they would look at it. They didn't find anything else wrong and did another alignment. and it was off again. Does anyone know what might be causing this?

This can be in the p/s rack, or a binding upper strut mount or even a tight tie rod end. This is probably over Sear's head.

Check front subframe mounts also...the whole cradle could be shifting around....