An easy way to find vacuum leaks is to start the car, let it warm up a bit, and then lightly spray some carb cleaner over the vacuum lines and listen for a change in idle. If you hear the change, spray that spot again to be sure. Check the point that you found to look for splits or cracks in the hose or hoses. Sometimes it's as simple as a hose coming loose from it's connection. Has it thrown up the check engine light on the car yet?