How do you get an object to stop moving when i rotate

Hi I'm trying to make an AI for a tank game and i can't figure out how to make it turn.. When i set the rotation and try to slerp it, it seems like it only do some of the turn befor moving again

 public Transform player;
 public float playerdistance;
 public float followdistance = 150f;
 public float roatationdamping = 2f;
 public float speed = 15f;
 public float wallcheckdist = 10f;
 public LayerMask obstacles;
 private Vector3 movedir;
 private bool ismove;
 private Vector3 ismoverotold;
 // Use this for initialization
 void Start ()
 {
     ismove = true;
     ismoverotold = transform.rotation.eulerAngles;
 }
 
 // Update is called once per frame
 void Update ()
 {
     playerdistance = Vector3.Distance(player.position, transform.position);
     if (playerdistance < followdistance && playerdistance > 1f)
     {
        // lookAtPlayer();
         sogoodshoot();
     }
     //else
     {
         
         turn();
         if (ismoverotold.y > transform.rotation.eulerAngles.y-2 && ismoverotold.y <transform.rotation.eulerAngles.y+2)
         {
             move();
         }
         
     }
     

 }

 void lookAtPlayer()
 {
     Quaternion rotation = Quaternion.LookRotation(player.position - transform.position);
     transform.rotation = Quaternion.Slerp(transform.rotation, rotation, Time.deltaTime*roatationdamping);
     transform.Translate(Vector3.forward * speed * Time.deltaTime);
     ismoverotold = rotation.eulerAngles;

 }

 void sogoodshoot()
 {
     
 }

 void turn()
 {
     if (Physics.Raycast(new Vector3(transform.position.x, transform.position.y, transform.position.z+2), transform.forward, wallcheckdist, obstacles))
     {
         if (ismove)
         {
             ismove = false;
             movedir = choosedir();
             Debug.Log("direction choosen");
            
         }           

     }
     if(!ismove)
     {
         transform.rotation = Quaternion.Slerp(transform.rotation, Quaternion.Euler(movedir.x, movedir.y, movedir.z),
                Time.deltaTime * roatationdamping);
         ismoverotold = movedir;
     }
        
 }

 void move()
 {
     if (!ismove)
     {
         Debug.Log("moving");
         ismove = true;
     }
     transform.Translate(Vector3.forward * speed * Time.deltaTime);
     
 }

 Vector3 choosedir()
 {
     
     System.Random ran = new System.Random();
     int i = ran.Next(90, 180);
     Vector3 temp = new Vector3();
     temp.x = transform.rotation.x;
     temp.z = transform.rotation.z;

         temp.y = transform.rotation.y + i;
   
  
     return temp;

 }

}