I did something wrong with my running script...the player is not bobbing when running?

sorry im still a noob at scripting... and i got the sprint function to work but whe i run the dude does tiny hops super quick and does not look right... it looks like it is glitching here is my code, it is in java script...

 #pragma strict
     var NaturalSpeed = .001;
     var tempSpeed : float;
     var Naturalbump = 1;
     
     var SpeedMultiplier = 9000.3; // for 20% speed increase while sprinting
      
     var moveDirection : Vector3; //this determines which direction we should be moving towards
      
     function Update()
     {
    
     moveDirection = Vector3.zero; //this rests our move direction to nothing so we wouldn't move unless movement keys were pressed
     tempSpeed = NaturalSpeed; //this rests our speed back to natural speed
      
     //this is just a simple movement check for demonstrating sprint; use your own methods of course
     moveDirection.x += Input.GetAxis("Horizontal");
     moveDirection.z += Input.GetAxis("Vertical");
     if (Input.GetKey(KeyCode.W))
     {
     moveDirection.y +=2;
     }
     else{
     moveDirection.y +=0;}
      
     if(Input.GetKey(KeyCode.LeftShift)) //this checks to see if the player is holding left shift
     {
     tempSpeed *= SpeedMultiplier; //this increases our speed by the multiplier
     }
      
     transform.Translate(moveDirection.normalized * tempSpeed * Time.deltaTime); //this moves our player to the correct direction at the determined speed (sprinted or not), smoothed over time
     }