I'm using 2001 mitsubishi evo 7. The intermittent eml was sensing the Oxygen sensor was faulty. I changed it with 2nd hand O2 sensor evo 7 twice. After driving for 20 miles the eml light appear again. And it still detects the O2 sensor is faulty. For your information, the eml only appear when i drive at 70-80 mph for about 20-30 minutes. when the intermittent eml light appears my car will lose power and the oil the oil pressure will drop, boost meter will increase and the car seems to lose it's power and the engine almost die. What should i do. Is there any misfire causing the O2 sensor to be faulty. Or is there something else