Character controller jitters when moving down the slope.

Hey guys, I followed a tutorial for a 3rd person controller so far everything seams to be working fine but only one issue, the game has a feature that lets you slide down hill, but for some reason for me it jitters/shakes like crazy, ive played around with the character controller values but it seamed to do nothing, i have no idea whats causing it to jitter that bad. I was wondering if anyone else had this issue and has a solution. Thanks in Advance.

Here is the code for the slide:

 void ApplySlide()
     {
         if(!TP_Controller.CharacterController.isGrounded)
             return;
         slideDirection = Vector3.zero;
 
         RaycastHit hitInfo;
 
         if(Physics.Raycast(transform.position /*+ Vector3.up*/, Vector3.down, out hitInfo))
         {
             if(hitInfo.normal.y < SlideTrheshold)
                 slideDirection = new Vector3(hitInfo.normal.x, -hitInfo.normal.y, hitInfo.normal.z);
         }
 
         if (slideDirection.magnitude < MaxControllabaleSLideMaginitude)
             MoveVector += slideDirection;
         else
         {
             MoveVector = slideDirection;
         }
     }

Here is the link to the full Code in pastebin:

http://pastebin.com/2ctn3t2n