how can i stop my 1.6 mrk2 golf idling irratically? ?

my mrk2 golf is idling irratically. It used to drop back to a normal idle speed but rarely does now. idle speed gets progressively faster! i cant find a leak in the vacuum hoses. one of the hoses at the back of the carb was damaged and i replaced it 6 months ago. ive fitted new wax stat. hose to the vacuum unit (green ball) was off recently. inlet manifold is OK! Think the fault is related to faulty vacuum I need some Help......