Couple things come to mind. -improper caliper operation -abnormally worn brake pads -rotor plate abnormally worn -even a suspension missalignment
That happens when you drive too close to the kerb and rub the sidewalls. This can damage the sidewalls enough to give you vibration or wobble at high speeds.
if is model with computers etc,most probable cause is the cam positioning sensor
It can be very dangerous especially at high speeds in a curve. It causes the rear of the car to become very unstable.
cranck sunser
You don't say what kind of car you have and some don't shift at higher speeds. Adjust the throtle cable and that should help if possible,.
It is according to when you feel the vibration. If you have a vibration at higher speeds, your driveshaft could be out of balance. At lower speeds, you may actually have a cracked engine mount. Take it to a shop before it tears something up.
We had this problem on one of our work trucks, ended up to be a bent rim.
Striking a curb, hitting a pothole at higher speeds. Defective Tire. Striking a curb, hitting a pothole at higher speeds.
Chattering/vibration at all speeds. Chattering when brakes are applied. Poor fuel economy. Noise.
Most likely its your tires. Could just need balanced. Or you might have uneven wear making it shimmy.
Tire out of balance is the most common cause.
Stereo interference?
Warped brake rotors will cause pulsation (or vibrations at high speeds) when the brakes are applied. This may also go on to misalign the calipers and cause other vibration related damages.
When you are moving at higher speeds, it could need alignment (if it pulls one way) the wheels may need to be balanced, air accordingly to the tire needs. If it is stopped.. timing?
well... there are many different causes for vibrations. The most common cause for steering wheel vibration at high speed is poor wheel alignment.
You need to check rotors and brake pads one or both are failing.
To fit both those symptoms it would be a vacuum leak, check all the vacuum hoses and the intake