I have an 08 Lariat F150 4x4 and over the last couple of months I have been getting some feedback out of my steering wheel....It is kind of hard to explain but it is like when you go to turn around a corner it is like you can feel it rubbing or like you can feel something through the steering wheel when you make a turn or like turning on an on-ramp that wraps around and when you are gradually turning the steering wheel??...

I took it to the dealer back home over x-mas break and they said that it was the power steering pump so they replaced it and that didn't fix the problem so I then took it to the dealer here at school and of course it wasn't doing it when I took it there or we couldn't get it to do it when I went out with the mechanic...They told me to watch when it does it again and then see what the truck is doing when it does it but all I can really tell is that when you first drive it for the first 15-20 minutes it won't do it and as you progressively drive it for a good period of time it will develop and you can feel it....I hope you kind of understand what I mean...It has the stock 20's with pirelli's and everything else is stock....

What are the possible parts in the steering that it might be from what I explained???