would this bad O2 sensor cause the car to chug at highway speed in high gear?

 

Unplug the O2 sensor & measure resistance between the 2 same-color wires (black?). Should be 10 to 40 ohms. Failed sensors usually go open-circuit. If the sensor's OK then we gotta go figure out wiring problems in the car.

 

ok. will try that. Honestly I'm thinking the O2 sensor is just gone because I have not replaced it in 6 years.