vaccuum leak?

Ditto on rebuilt carbs, I had idle issues with the 64 170 in the wifes car, it had a rebuilt or reman carb on it when we bought the car. I rebuilt the carb and still had issues. Plain fact was that a forty plus year old carb was worn to the point of not being any good. In my case the thorttle shaft was worn enough to cause a vacuum leak and idle issues. I found a new Carter in the box from the early seventies, changed a few gaskets and Viola... no more idle issues...