I own a W203 C180 2001. I experience a noticeable vibration while driving after the car has been standing still for a while. This vibration starts at around 50km/h. I feel it in my seat and my steering wheel, you can visually see the steering wheel vibrating. For example when driving to work in the morning, or when I leave work. I've checked the following:

• Rims and tires. All wheels were balanced, neither the tires or the rims were warped according to the guy who did it.
• Checked both front wheel bearings. Disassembled and greased up. Tightened appropriately. Bearings were found to be in good condition
• Checked the suspension. Ball joints, tie rods, shockers, bushings, etc. Only thing I found was a broken spring at the rear, nothing that has anything to do with the vibration.
• Checked the center support bearing for the drive shaft. Good condition.
• Changed brake rotors and pads at the front wheels, since I suspected the rotors of being warped. Didn't help.

I also tried putting the car in neutral when cruising at 50-60km/h (usually where I feel the vibrations at most) and didn't help.
Also worth mentioning: I hear weird sounds coming from the power steering when turning at stand-still or very low speeds. Could this also be the issue?
Does anyone have any ideas for me at all, please leave them in the comments. This vibration is driving me ****ing crazy, especially when I can't localize the issue!