Cooling System Problem?

[kyasarin]

I have a 1998 SL2. About 2 or 3 months ago, my service engine soon light came on and when I had it checked I was told that I probably had a bad sensor on the engine temperature. I can't remember what the technical name for it is. It will cost me about $100 that I don't have right now to have it fixed. Since I have owned the car, for about a year now I have always had to keep a check on the oil level and top it off about every week or so, but I heard that this is common for saturns to burn through oil. Well, the engine temperature gage on the dash inside of the car is reading normal and I don't know if this data comes from that sensor that is bad or if that is something seperate. Tonight, my car stalled out on me. I cranked it back up fine and didn't have any problems on the way home, but I noticed that the rpm gauge needle jumped a few times, which worries me. There is something going on with the engine and I think that it may be running too hot because when I checked the oil level, it was down again and I just filled it up a week ago. I mean it was almost all the way down on the oil stick. It is not leaking oil. I changed the oil 3 months ago and the oil is black now. Also, the ambient temperature around the engine felt much hotter than usual, and I also smelled a bit of a burnt smell. I need help. I have not checked the engine coolant level yet, because the engine was still too hot, so I will do that in the morning. Is is possible for me to replace that bad sensor myself?