You don't want to pull out any pin feathers...they are the new feathers replacing old ones that have fallen out naturally.....why did her previous owner think the plucking was from depression ? ? ?
If she was travelling with him in the truck, I wouldn't think she would be depressed...from your pictures, it looks like she may have been barbering her feathers...barbering is when they chew on their feathers, although I'm not quite sure it was caused by air sac infection.....you really need to take your bird to an avian veterinarian for a bird physical.....
There are other birds that live in the trucks their owners drive, but trying to figure out what might be wrong with a bird that you have recently acquired by searching around the internet is not a good way to care for the bird.....an infection of its air sac(s) is a serious condition and will require proper veterinary treatment and/or medication that you can't get at a pet store.....
The only thing & noticed in your pictures were the new pin feathers and the barbered feathers on the one wing.....off hand I can think of about 30 things that could have caused your bird to barber her feathers, but treating for the wrong thing could well create another problem.....how often do you let her bathe; what kind of a diet do you feed her; how large is her cage; how dry is it at your house (humidity in the house); how much out of cage time does she get; does she play with her toys; have you ever seen her pluck any feathers; have you seen her barber any of her feathers; did her previous owner smoke; does anyone in your house smoke?
Good luck.....