Gas/Brake pedal vibrating

Hey all. Having some more problems with my "new to me" 2000 Chevy Malubu. There seems to be some problem with the Gas and Brake pedals at random times where the pedals start to vibrate while coasting, but goes away once I apply pressure to the brakes. Anyone ever seen or heard of something similar to this happening? I'm clueless right now.

I would check the engine mount first thing. Then look at the front tires for odd wear patterns. Switch them back to front if you want to rule out a tire issue, which could be balance related. Since it goes away when you use the brake, I doubt that you have a brake problem, they get worse if you have a bad rotor. Have the front end checked too.