Sounds like my 2002 4.6is, I get a left to right vibration/wobble in the steering wheel between 60-70 MPH, just started about two months ago,I too have a weird wheel squeak, can't tell which wheel though. I went and had my wheels road forced balanced and had the alignment checked, still there.

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2002 X5 4.6is
1999 C5 Corvette
1992 Mitsubishi 3000GT VR-4
1994 Kawasaki ZX-9R
2005 Mazda 6 Wagon (Wife's)
1991 Mitsubishi 3000GT VR-4