Thanks for the help.
Replaced DPFE and fuel filter and it seems to be running fine now. The catalyst code never reappeared so I'm not worrying about it right now.
I did determine that the DPFE is the same for the 3.0 and 3.8, though I wound up replacing it with one off a 3.0. Oddly, neither the old or new sensor passed KOEO test I found here:
http://rockledge.home.comcast.net/~r...tage-Test.html but maybe I was just doing it wrong.