^^ most likely a motor or tranny mount, put up the e-brake and get a friend to let the car in gear slowly and give it a little gas (it's called brake-torquing) try it in 1st and then in reverse, what you're looking for is excessive movement of the engine, that'll let you know if there's a mount bad, while they're brake torquing the motor you'll be looking at the mounts to see if any are broken, gl