Vacuum issues will cause you the problems you have listed, however if the injectors have not been changed ever from new no harm in changing them. (they are "not that expensive - relatively") I would solve you vacuum issues first though. All rubber pipes and vacuum pipes should be replaced with a car of your age. Change the rubber hoses that feed your idle air actuator.

The first place to start with any Benz this age is
(a) electrical - Distributor,rotor,plugs and leads, grounding.
(b) Vacuum leaks.
(c) Fuel problems - Injection systems