Volvo Repair: Idling Problem, volvo 940 gl, vacuum leak

Question
After my 1992 Volvo 940 GL began skipping gears a few times accelerating the vehicle faster, the car showed up a nasty problem when halted at traffic light; the RPM dropped beneath 900 to around 500 and then the engine began shutting off! I drove back putting the gear to Neutral at each light stop and realized that the engine went to 1,100 RPM at idling to stay on. It works fine on higher gears but the idling prob and stopping has set in. What could the problem be?  

Answer
            Hello Greg,

                      To answer your question...I need much more info....Solving your problem could be as simple as...vacuum leak at a hose connection..gasoline problem...or a minor adjustment to one of your idle system.
               It could also be...a fuel press regulator..or perhaps a elect.idle stabilizer.
             Good luck,

                     Bilbo