u/Massive-Welcome9465

Hello! Idk anything about cars so I figured this might be a good place to ask!

I have a 2006 Chevy cobalt and sometimes when I drive over 45-55 the car starts to shake/vibrate pretty bad and the break pedal will get stiff and not push down a whole lot but still breaks okay. If I turn it off for a little while it usually goes back to normal but if I continue to drive it while it's shaking like that it starts gets sluggish while trying to accelerate. I've had a mechanic drive it a few different times and then of course it'll drive just fine like it has a mind of its own lol. (It'll also occasionally turn off when I put it in park idk if that's related.)

The tires and break pads are fairly new. If you have any insight I'd appreciate it 🙂