new tricks - the painless instructions say:
" A VACUUM HOSE FROM THE SWITCH TO A PORTED MANIFOLD VACUUM SOURCE THAT ONLY HAS VACCUM WHEN THE THROTTLE IS OPENED."
then there is a note at the bottom of the page:
"IF YOU ENCOUNTER A CONSTANT LOCK-UNLOCK SITUATION IN CITY TRAFFIC A VACUUM VALVE (STANDARD IGNITION #DSV31 ) MAY BE INSTALLED IN THE VACUUM SWITCH HOSE TO CORRECT THE PROBLEM"
http://www.painlessperformance.com/Manuals/60109.pdf