My 2001 Chevy Tracker quits running after a while and will restart after about 10-15 minutes. It originally runs rough after it restarts. I have been told to replace the camshaft sensor. Also, when I give the tracker gas I get a bad odor similar to ammonia.

Had the same problem with my tracker. Replaced the camshaft position sensor(easy to do yourself, takes about five mins.) Now can drive at highway speeds for about a half hour and stop at the gas station and she'll start back up and run fine. Before i had to wait at least 15-20mins before she would start. Also, if your service engine soon light is on take it to the national chain auto parts stores and they will hook up the code reader for free. The sensor runs about $120.