I have a 90 PU with 22r. When I turn the AC on, the diaphram pulls and increases the idle as it should but when i turn the AC off it does not release the vacuum to decrease idle. I have to actually pull the hose off of the idle up diaphram before it will return to normal idle. How does the VSV release vacuum once it is turned off?

 

You can wd40 the VSV, Also make sure the vacuum hoses are correct, If there backwards it can do that.