I am trying to use these motors because they are high torque. I am trying to power them with an arduino and they keep moving erratically spinning both forward and backwards and not...

I am trying to use these motors because they are high torque. I am trying to power them with an arduino and they keep moving erratically spinning both forward and backwards and not moving as instructed. I have tried a number of things including powering them with a separate power source, using a capacitor too smooth out voltage but nothing seems to be working. Does anyone have any suggestions?