Why does my truck steering bad?

i have a 97 chevy s10 and my steering is a little bad. when im driving down the road espically on the highway the steering likes to play from left to right a lot and is a little unsafe. i took my truck to have it allinged the technician told me i had lots of worn parts such as ball joints, shock absorber, lower control arms, and pitman arm, i had another tech fix it due to price he did every thing except the pitman arm, as he said the one it had was fine. yet the truck still likes to play while driving could this be due to pitman arm