[C#] Enemy flys at Player

So im having abit of problems with my EnemyAI script. The script works fine on a flat ground but if my player say, climbs a mountain, instead of the AI trying to follow him up the mountain, he just flys at him. I have tryed adding a Character Controller as well as a ridged body to the enemy to attempt to get it to stay on the ground. The character controller had no effect no matter what setting is applied to it, and the ridged body fixed the problem but created another one. It causes the enemyAI to glitch out and twitch when it reaches the maximum distance from the character where it normally would stop getting any closer. Code below, thanks in advance.

 using UnityEngine;
 using System.Collections;
 
 public class EnemyAI : MonoBehaviour {
     public Transform target;
     public int moveSpeed;
     public int rotationSpeed;
     public int maxDistance;
     
     private Transform myTransform;
     
     
     void Awake(){
         myTransform = transform;
     }
     
     
     // Use this for initialization
     void Start () {
         GameObject go = GameObject.FindGameObjectWithTag ("Player");
         
         target = go.transform;
         
         maxDistance = 3;
         
         
         
     }
     
     // Update is called once per frame
     void Update () {
         Debug.DrawLine (target.transform.position, myTransform.position, Color.yellow);
         
         //Look at target
         myTransform.rotation = Quaternion.Slerp (myTransform.rotation, Quaternion.LookRotation(target.position - myTransform.position), rotationSpeed * Time.deltaTime);
         
         if (Vector3.Distance (target.position, myTransform.position) > maxDistance) {
             
             //Move at Targets
             myTransform.position += myTransform.forward * moveSpeed * Time.deltaTime;
         }
     }
     
     
     
     
 }