Intake leaks can cause a poor idle and will not let your car run smoothly. One of the most common leaks are injector o rings, they dry out and crack letting air pass. An intake leak in this area can be checked by spraying carb cleaner. If the idle changes, you found the leak! First, try the o rings, if a leak persists, replace the sockets. see page 50 for the tools make the job easier.