Character controller teleports all over the place

Unity Engine
1

When my character controller turns 90 degrees, the rotation happens while the character is moving and it looks really smooth. However, when I turn the character 180 degrees (ie. Pressing up and then pressing down) the controller literally “teleports” a couple units. For example, pressing up for awhile and then pressing down will make the character jump down a unit or two. This teleportation also happens when a directional key is released and than another is pressed - regardless of angle.

Is there a way to fix this? Here’s the code I’m using:

using UnityEngine;
using System.Collections;

public class LukaCController : MonoBehaviour {
	float speed = 15.0f;
	float gravity = 40.0f;
	bool isMoving;
	Vector3 moveDirection = Vector3.zero;
	Quaternion originalRotation;
	// Use this for initialization
	void Start () {
	
	}
	
	// Update is called once per frame
	void Update () {
		CharacterController controller = GetComponent(typeof(CharacterController)) as CharacterController;
		if (controller.isGrounded)
		{
			moveDirection = new Vector3(Input.GetAxis("Horizontal"), 0, Input.GetAxis("Vertical"));
			moveDirection = moveDirection * speed;
			if (moveDirection != Vector3.zero)
			{
				transform.rotation = Quaternion.LookRotation(moveDirection.normalized);
			}
		}
		//Apply gravity
		moveDirection.y -= gravity * Time.deltaTime;
		
		//move the controller
		controller.Move(moveDirection * Time.deltaTime);
	}
}
2

Is there anyone who has a suggestion? This problem is a lot worse than it sounds and I don’t know where to begin on fixing it.