Drag rigidbody.js help

Hi I am working on a game that is just like amnesia where you can solve puzzles by moving objects around.i have found a dragrigidbody.js script already in unity3D but there is 2 problems I am having, 1.when I move forward with the object in front of the player it forces you to move slower 2.when I raise the object it rotates too much and falls to the ground slowly.

all I need help is to tweak the script so these problems dont happen anymore. I would do it my self but I am a beginner at scripting and dont know where to start in the script.

please help me so I can move on with the game

thanks in advance.