Help understanding Windstar codes

Just had our 1999 Windstar read out with codes po171.po174,po401.po402. Looks like an inherent problem with these vans. We have one symptom of it running rough at about 30mph but if you accelerate it goes away. I read the other posts on ideas to fix this. Is it safe to keep driving or take it out of town? Thanks for the help.......

Here is the best reference to this infamous codes:
http://leckemby.net/windstar/windstar01.html

From what others have posted......the fuel economy will not be very good until this is repaired.

For the P0401/402, I would buy a NEW DPFE and replace it.
This is a quick repair that will help at least that part of the problem.

Thanks for the replies, we will try all you've suggested