How in thee world do I unplug the downstream O2 sensor on a 99 sebring 2.5L convertable??????

 

look at the new o2 sensor and look at the clip that holds the connections together

 

Not sure about your '99, but if it's like my '01, you need to lift the little plastic retainer that prevents the plug from coming apart. I stuck a tiny screwdriver in there to lift and hold up the clip while I pulled the plugs apart. Practice on one that's easyto get to.