1999 Chevy S-10 Blazer mileage: 89,000. When I first purchased this vehicle, a 1991 Chevy S-10 Blazer 4.3L (Tahoe Package) 2WD Automatic, I had noticed that the check engine light came on while driving and then went off. Having spent some time working as an automotive parts person in retail, I knew how to check a GM's ECM codes, and did so. The code came back as 13 (Oxygen Sensor Circuit)--thanks to my fix-it manual. Anyway, having had this problem in the past with other vehicles I had delayed in rushing out and buying the part, thinking it would be a minor problem, I could attend to later. As I was driving home last night, I had been running for about ten minutes, when the car seemed to lose power and the alternator gage dropped, it recovered itself and a few seconds later when I came to a stop at a light, it cut off. I restarted the vehicle fine, and continued. Coming to a stop a few seconds later, it cut off again. I once again restarted the car and made it home. Figuring this must have something to do with the O2 sensor, since the check engine light had come on once again before cut off; I drove down to my local auto parts place to purchase one this morning. I had been running about five minutes when I came to a stop at a light and the car once again died. Ignorant in thinking it would restart, I tried to crank it. The engine rotated but would not start. I proceeded to do the frustrated person thing of continually trying to turn the engine over to no avail. I had noticed the check engine light had once again come on before cut off, and once again checked it, but there were no new codes, still the 13. I had to be towed home, where the car started fine and I left it. I have not been able to replace the O2 sensor today because in difficulty in getting to it, and the fact that I haven't the strength to turn the darn wrench! (Which only further frustrates me) But, the car has started numerous times since then, although I am paranoid to drive it anywhere for fear that it will cut off. I intend to replace the O2 sensor and spark plugs today, but have this dreaded thought that the problem surely cannot reside there alone. I can't imagine the car would cut off because either are faulty. Can you please help? Could this be the problem, or am I looking at something more serious?