I'd check for play in the wheel bearings and the bushings/balljoints. Are the tires wearing funny on the front end, that is usually a good indicator of where something is going wrong. It could also be a power steering pump going bad (I don't know if 05 has an electric or a mechanical powersteering pump). But atleast it might give you another area to check.
1990 Mustang GT with AOD transmission-quite a bit done to it. First mustang I had, & still have.
2003 Mustang GT-Total lost by a friend into a golf course. RIP GREY GHOST
2002 Dodge Ram Quad Cab 4.7liter, auto transmission, towing package
1988 Mustang GT convertible with manual transmission- BONE STOCK! New IAC (because it idled at 2500 rpm)
1990 Mustang GT Convertible with AOD transmission project car & building it for a friend