Suggested code based on your original script:

Code:

---

// Global definitions:
define enemy_number,	SKILL51;
var max_enemy_count = 5; //max_enemy_count = 5 or whatever, can be changed in script
var enemy_count = 0;
 
// Actions:
 
action enemy_creator
{
		my.passable = on;
		my.invisible = on;
		while(1)
			{
				if(enemy_count < max_enemy_count)
				{
					//get a randomized position here before creation if you want
					ent_create("speeder.mdl",my.x,enemy_flight);
				}
				wait(5);
			}
}
 
action enemy_flight
{
	enemy_count += 1;
	my.enemy_number = enemy_count;
	while(1)
	{
		// set this entities enemy_number to 0 whenever you want it to die
		if(my.enemy_number == 0)
		{
			ent_remove(me);
			enemy_count -= 1;
			// break; // automatic when enemy entity is removed
		}
		wait(1);
	}
}

  

---

cheers