I've got an '06 F150 and the steering isn't right with it. It has had a heavy feel and is almost like the power assist is only working half as good as it should. It's been like this for a couple months. I 've had all four ball joints and the steering rack replaced in the last month. It had the heavy steering feel before and after everything was replaced. It also doesn't recover itself on sharp turns, I have to turn the wheel back as I complete the turn. Could it be the power steering pump? I thought it was a mechanical device and it either worked or it didn't, maybe they get weak? Any thoughts would be appreciated. Thanks.