My O2 is dead and I cant find the right replacement. My O2 is an abnormaly small one and all the ones I have ordered are to big to fit in the hole and thread in. But they have all had the right connecter and the right wire harness. Any ideas as to where to find the right one?

http://www.courtesyparts.com/

they should keep them in stock...

What are the symptoms of a bad 02 sensor? Is it simply an ECU code or will the engine run rough?

Well depends on how you look at the O2 sensor... Some of the symptoms are if you look through a DVOM (digital Volt Ohm Meter) that it is WAY off from any normal O2S reading. Like you should be seeing around .4-.6v if its reading 1.0V then down to .1V or any combo of that odds are your O2S is gone bad. Also your ECU is well aware of what it shoud read and will set codes if its not in those peramiters. Your Check engine light WILL come on for a O2S fault. Just becareful installing the new O2S dont get anylocktite on the sensor head itself, it will fowl the sensor.