Weird Clamp command issues.

I try to build an fork lift and i need some clamping for the lift(y) and the fork(x).

Each time my fork reach the clamping limit; my fork move on Y or Z for no reason. How i can fix this ?

video showing the bugs : link text link text

There the script i use.

 using UnityEngine;
 using System.Collections;
 
 public class mathftutor : MonoBehaviour {
 
     public Transform pos;
     private float mover;
     // Use this for initialization
     void Start () {
     
     }
     
     // Update is called once per frame
     void Update ()
     {
         //this is used to get use left and right arrow input
         mover = Input.GetAxis ("Horizontal Right") * Time.deltaTime * 20;
         //now we use translate to move the character
         transform.Translate (mover, 0, 0);
     
 
         transform.position = new Vector3 ((Mathf.Clamp (transform.position.x, -2, 2)), transform.position.y, transform.position.z);
 
 
     }
 }