there are many components that control the steering, one would need to inspect the condition of those components to tell you what is causing this problem. most of the time it will only be one or two of the components to get everything working right again. You have upper and lower ball joints, idler arm, pitman arm, inner and outer tie rods, steering gear or rack and pinion, also components of the steering column it self. I know this isn't much help but you can take it to a local tire and alignment shop and get everything done you need.
Hi. Was having similar problem so put it in for alignment-it was way out so they said-the toes and camber etc. Cost me about 120 for that-then had them check further and it also needed motor mounts-not sure they are related. but that is another 500.00