Vacuum leaks cause a number of problems-performance is most certianly one of them-fuel metering or mileage is hit also. Good luck finding the spot your leaking air-fix those air leaks they cause trouble.
one good way is to use propane, attach a length of about 1/4 id hose to propane bottle a couple ft long open the valve and just move the hose around the intake if the idle picks up you found the leak. On ething to ck on these cars is the crakcase ventalation valve, it will cause an internal vacuum leak that you wont be able to find with propane or other external methods. The valve have a rubber diaphram inside that detieriates and will give you all kinds of running problems
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