On a side note to this yesterday I changed out one of my pre-cat 02 sensors. I had an aftermarket one in there and finally got around to replacing it with a Bosch one I had. Wjen I started the car the idle was awful. It was similar to when the battery is reconnected after a disconnect. Almost stalling. Lights on dash. I had to give it gas to even the idle out, it was very rough. Is that normal for changing out an o2 sensor?? It ran fine on the Highway as usual. I took it for a 15 mile ride and it seems fine after that.