I recently "just" passed my emissions test with some tweaking from my
mechanic. He told me to get it tuned right away to remain in compliance. I
knew I was overdue for a new O2 sensor so I replaced it with the Ford
equivalent (13913), and noticed no improvement in the way the engine ran. 
In fact I observed white exhaust at low idle and water dripping out of the
tailpipe. On closer inspection I noticed a couple of wet places on the
pavement under the catylitic converter. It was clear that water had been
dripping from the CC for some time because there was rust in the spots
where the water was dripping.  Any idea where all this water is coming from
(please don't say head gaskets)?

Mark Bowie