2000 Saturn SL2 oxgen sensers

You have two o2 sensor's one in the exhaust manifold and one right before the cat. When they go bad they usually set a code and don't have any symptom's. Why don't you tell me what your car is doing.

If you have to give it gas to start I would say you have a bad coolant temp sensor. Pretty common for them to go bad and cause all kind's of symptom's. There only 10 make sure you get a brass tipped one the plastic tipped one's crack. When you change it make sure the engine is cold you will loose coolant. When you change it make sure you inspect the connector going to it if it's corroded then you need to change the connector too. They usually turn green or blue when they do I emailed you a diagram of where the coolant temp sensor is. Give changing that a try and let me know what happens.