I just bought a 1997 Galant, it runs great. I noticed that after about 40 mph the slightest movement of the steering wheel causes the car to feel like its swaying left and right, almost feels like the car is on marbles and someone pushes the front drivers side fender and a second later someone pushing the rear straitning the car out. Hard to explain, but I have no clue what this could be, suspension problem? Please help!

 

Check the tire pressure.

 

alignment