Your O2 sensor will not keep the car from running, just running rich. And because of that, clean your spark plugs.

the fuel pump relay buzzes sometimes -- get a new one if the solder didn't work.

something wrong with the alternator -- That WILL keep your car from running and is probably your biggest problem. Check the voltage and change the brushes and then check the voltage again. After you get 14V from the altenator, then check the voltage regulator to make sure it is constant.

there's a connector, that plugs into what sort of looks like a spark plug, or o2 sensor, right above my alternator that runs into the engine block -- Sounds like your temp sensor. Make sure the wires are not broken and tape them up securely. Also will cause minor drivability problems.

There may be a short in your wiring harness, draining your battery. Check the voltage drop as you pull fuses, one by one, with the key out. Don't forget the fuel pump fuse.

Klaus
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98 V70Rawd(108Kmi), 95 854T(88K mi), 75 164E(173K mi)