just o2 sensor?

I have a 2001 chrysler voyager, I know the o2 sensor is bad. The check engine light has been on and we had it coded. Fuel use getting bad, all that. Today I went to lunch and the check engine light blinked on and off every so often, when it did it would idle rough (that was when I was going slower, I when I would speed up it ran fine and the light stopped flashing but stayed on), and the van was heating up, not in the red, but about a quarter more than normal for the van. So I naturally I checked the antifreeze. It's full, so I am wondering does the o2 sensor make it run warmer than usual also or is there another problem?

Blinking indicates a misfire.

The O2 sensor will either lean or enrichen the fuel/air mixture by adjusting how long the fuel injectors open (via the PCM), depending on the amount of oxygen it detects in the exhaust. The leaner the mixture the warmer the engine will run. If the blinking was a regular event every few seconds it indicates the system is malfunctioning to the point it will damage the catalitic converter. This could be the sensor or anything that creates a lean condition such as a weak fuel pump, clogged injectors, etc.

Which O2 sensor fault code? There are several fail modes.