struts and springs and tires. check inflation of your tires first. push on the hood- if it doesn't bounce right back up its in the suspension like struts and springs.

check the tire pressure.

edit: tire is the most obvious bc they are only part of the car that's touching the road. If not the tires then maybe a bad wheel alignment or a leaky power steering.

Have you recently replaced your tires ?? Changing to a 'low profile' tire can affect the ride.

Either your tires need replacement or they are low on pressure.