Help with object spawning bug

Hi there,

I'm having trouble with a little bug involved in a part of my game where I spawn several objects simultaneously. For some reason, the script will perform as intended for a few seconds, and then the spawn points begin to rapidly spawn objects like crazy (many more than the limit of 3 I include in my script.) I'm not sure where the problem lies on this, and any help is appreciated.

 void Update () {
 
         tileSpawner();
 
     }
 
     void tileSpawner()
     {
 
         //This section below will run every time that the time clock in game is equivalent to the value
         //"cutOff" which is just the game time plus two seconds.  It gets reset at the bottom of the statement
         //every time it is run, essentially throwing another two seconds on the clock before it gets run again.
         //It appears that for whatever reason, the tileSpawner funtion is just being run indefinitely at a certain point.
         if (Time.time >= cutOff)
         {
             x = Random.Range(0, 8);
             y = Random.Range(0, 5);
             first = x;
             tilePrefabs[y] = Instantiate(tilePrefabs[y], spawnLocations[x].transform.position, Quaternion.Euler(0,0,0)) as GameObject;
 
             
             while(first == x)
             {
                 x = Random.Range(0, 8);
             }
             second = x;
             y = Random.Range(0, 5);
             tilePrefabs[y] = Instantiate(tilePrefabs[y], spawnLocations[x].transform.position, Quaternion.Euler(0, 0, 0)) as GameObject;
 
 
             while(first == x || second == x)
             {
                 x = Random.Range(0, 8);
             }
             y = Random.Range(0, 5);
             tilePrefabs[y] = Instantiate(tilePrefabs[y], spawnLocations[x].transform.position, Quaternion.Euler(0, 0, 0)) as GameObject;
 
 
             cutOff += gapTime;
         }
     }
 }

This is the code that is responsible for destroying the object.

     void Start () {
 
         tileDeathPoint = GameObject.Find("Killer");
     
     }
     
     // Update is called once per frame
     void Update () {
 
         if(transform.position.y < tileDeathPoint.transform.position.y)
         {
             Destroy(gameObject);
         }
     
     }
 }