Crazy shaking in my Toyota Camry CE, 2007, automatic, 100,680 miles.

This will be a good bit. My car has been doing this sound like it’s accelerating while idle (rpm throttling) and shaking a lot when idle; also takes like 8 seconds to crank. But recently whenever I hold the break to slow down or hold the break while reverse, the car shakes a crazy amount. I have gotten new spark plugs, alternator was replaced last year, 2 new engine mounts(front and right side) and everything is fixed with the AC. I have taken it to 2 different shops and nothing has changed. I have it scheduled to go into a Toyota dealership to get check tomorrow but I have no clue.. hoping I don’t need a new engine or transmission. Thanks