Strange humming/vibrations in front of car and strange trembling in seat pedal and steering wheel

[Joe_shmoe01]

So I have a Kia stinger gt2 rwd, and I’ve been having an ongoing issue with trembling and vibrations in the front of the car. Going over bumps at lower speeds makes the car sway back and forth more then I’d like. It also feels a bit bouncy and doesn’t settle down. On the high way my car will make a humming/buzzing noise in the front of the car and sometimes slight grinding. Also at speeds over 100 my car shakes badly and it feels unstable . I have eibach sway bars installed along with cold air intakes and drilled and slotted rotors. I already suspect my break pads need to be upgraded because I’m getting shuddering after the car heats up. I just dont know what the issue can be. It can’t be the front drive shaft since it’s RWD and I’ve taken it to multiple mechanics who checked everything and said they saw nothing. Any ideas what could be happening here?

 

[Snicklefritz]

Do you know the history of your car?

There is no way that a properly maintained Stinger is "unstable" at any speeds. Trembling, vibrating, swaying back and forth, it sounds like you have more than one "issue". Your description sounds like collision damage

I may be misunderstanding you, but brakes never cause a vehicle to shudder after it heats up. If you meant after the brakes heat up from heavy use then yes, shuddering is caused by brake pad deposits on the rotors, in all likelihood. But only under braking conditions. You won't feel any shuddering from brakes just rolling.