You can break up the AI shooting randomly with something like :

while {true} do {
{

		if (random 1 > 0.83) then {
			_x setCombatMode "YELLOW";
		} else {
			_x setCombatMode "BLUE";
		}

} foreach allunits;
sleep 1;
};

This would lower the rate of fire overall by making pauses between bursts and shots.