No vacuum reservoir on gas engine vehicle. What you need to check is all
your vacuum hoses to make sure they are tight. Pull them out and put them
back on... on some connector, you can snip a bit off and put back on for
However, I suspect you have a large vacuum leak on the large black hoses...
they are on both side of the valve cover... spray carb cleaner at the end
cap and see if it affect the engine... I am pretty sure they will.
Other source of leak is by the idle control valve... the black hose fitting
there. Spray carb cleaner whereever you suspect may leak or not... and if
engine act differently, you definitely got a leak.