Thanks to all for your insight and suggestions - we messed around with pretty much everything that was suggested. In the end I think it was really just the O2 sensor and some dirty contacts, plugs and leads. So with a new O2 and a little cleanup we finally got the van running well at about 7pm last night. They stayed up here last night and we had a few (too many) beers to celebrate. As I write this they are already in Denver en route back to Cleveland.
Anyway, thanks to everyone for the help.

Paul Connelly