Ok, so I had the thrust arms replaced at RMP Motors and the car feels so much better now. The front wheels and steering wheel feel much tighter. The front end doesn't tremble when I hit an uneven surface any more (such as when entering a parking lot). The shimmy has been greatly reduced but it's still there, and I feel it especially between 120-125km/h. I feel this shimmy mainly in the gas pedal, floor of the car, and seats a bit.
I wish I can just go to a mechanic once and he tells me, "Fadi, this is what is wrong with your car. This is why it shakes at 120km/h!" Of course, life is not perfect and so are people, and mechanics are just human beings who try their best.
I just want to clarify that Rocco did not say replacing the thrust arms will solve the shimmy problem but he did say it will solve the trembling in the steering wheel when braking and the car will feel so much better to drive. And he was right: the steering wheel is so smooth now, and the front end feel so much tighter too. Actually, even the shimmy problem has been reduced a lot but it's still there around 120km/h.
I am very glad I replaced the thrust arms because the car drives so much better now, but I also noticed it's pulling to the left now. Driving on the highway, I constantly have to adjust the steering wheel because of that. Of course, after any change to the front wheels (such as replacing the thrust arms) I expect the car needs alignment, but I've already done that twice in the last 3 months and I am about to give up on this car. I know it's a great car but I feel that I am not getting any where with fixing it. I just can't afford to spend time and money on it without any results. I just want the shake problem being solved once and for all.
I am going to call Darren to see if the warranty of the tires and rotors allow me to replace them. The tires because they don't seem even when run on a balancing machine--at least to my untrained eyes. (Would road force balance solve this problem? I don't know. You tell me.) And the rotors because when braking there is a slight uneven feeling in the brakes.
Oh, I also want to thank Rocco so much for fixing my front bumper without charging me or even me asking for it! The car's right side of the front bumper was loose and I wasn't very excited about going on long trips with it like that, but thanks to Rocco now I am confident again to go places with the car. To be honest, I was happier about the bumper being fixed than the thrust arms!
PS: My car is really a great drive but I am one of those people who pick on every little thing. Every one who test drives it tells me that it's a great drive and better than anything they've driven. But I am not satisfied with that--I want that shimmy problem solved or at least identified.