Vacuum system

Have a 'ghost' problem with 300D'97 vaccum,help please, one black vaccum line came from the engine compartment and is not connected to anywhere-everything works well except the cold wether system on the IP- the engine doesn't starts well in cold, doesn't increase the rpms.When I put stopper on it, the enrichment systems became to work,cold weather starts are without problems,when the engine get hotter the rmps decrease...But...the flap on the ventilation system that opens/closes outside air refuses to open,only internal air ventilation.Please if have any information/diagrams on vacuum system,Help.