I have replaced the front shock absorbers of my 97 Catera, actually, i had it brought there by my father. I was trying to solve this loud thug sound when passing over bumps and craters here in New York. When it came back, the sound is not as bad as before, but still exist. And the funny thing is it is more prevalent when the car is driving slow and get over a hole ( like a manhole indentations along roads). I guess driving fast gets the car some momentum to just fly over them. Anyway, which part should i have checked in the front suspension assembly. Jeffrey, belated Happy birthday and thanks, you've been a lot of help for us owners of this car.

Check the control arm bushings, swaybar links, check for anything loose.

It could be your tires as well