'97 Jetta III Starting Complications

Whenever the temperature is above about 75 degrees F I have problems starting the engine. It takes longer for the car to start, and when it does it idles very low and usually dies unless I feed it gas. After 20 seconds to a minute the car evens out its idling. However, when it's this hot out sometimes the car experiences idling problems too. Sometimes when sitting at a traffic light, the engine will start to erratically idle and shut off. Any ideas as to what's causing this problem? Thanks,

Ben