Hydraulic Power Assist Steering System problems of the 2004 Toyota 4Runner

This is an e-mail I sent Toyota headquarters: I have had my new 2004 4runner limited back to the dealership (ron carter, alvin, TX. ) 4 times before I even had 500 miles on the vehicle. The reason is because of steering wheel oscillation/vehicle vibrations between 55 and 70 mph. The dealership re-balanced the wheels and tires that came with the vehicle (dunlap grandtrek at20) twice without any luck. I then had them upgrade the tires (for and additional $420) to michelin tires. This didn't solve the problem either. I then brought vehicle back in one more time the following Monday for another attempt to fix the problem. No luck again. All of this took place within 7 days of me taking ownership of the vehicle. Every time I took it in for this investigation, the service department told me that the problem was fixed (all 4 times). It was not fixed! I had the technician who balanced the tires (his name was tracy) drive the vehicle and he too noticed the steering wheel oscillation/shimmy. One of the service advisors (her name was kim) also drove the vehicle after a different attempt to solve the problem and noticed the same concern. 9/8/04 I'm still waiting on the Toyota regional office to contact me back like they promised to get this problem resolved. I really like this vehicle and would like to get this problem fixed. I'm not sure what to do next (lemon law?). I am writing Toyota to see what else can be done to solve this issue that the dealership could not. Fyi - the more I drive the vehicle in this condition, the more damage it's doing to my "new" tires as well as premature wear to the steering/suspension components. Fyi-still waiting for them to contact me back for resolution.