Worn mounts can cause torque steer and those vibrations you get at highway speed, and on accelleration from start it can creat a shudder with some steering wheel vibration.
How much does it cost to replace engine mounts?
For the price of parts, actual motor mounts themselves cost around $50 to $150. The labor to install these mounts and correctly realign your engine costs more than the parts themselves. Expect to spend anywhere from $200 to $450 in labor to replace a motor mount depending on how difficult it is to get to.