I've been having recent issues with my 00 eclipse GT (v6), I will get a decently loud engine knock when I start up the car on a low temp but after it heats up a bit, it goes away.

I also have been getting low gas mileage and ****ty acceleration a little while after my check engine light came on, I scanned my car and got the p0135 code saying it's the heating circuit to my o2 sensor (Bank 1 Sensor 1), is it stupid of me to think thats what's causing the performance issues to my car ?

The big mystery that's been bugging the hell out of me is why my engine will only knock at low temp then stop.

anyone have similar situations?