This is the first time I have posted here so I appreciate any help I can get. I have a 99 Ford Taurus with the 3.0 Duratec DOHC. The car has 62,000 miles on it. It runs rough and will sometimes die. It will start right back up. I know the 0401 code is probably the PDFE. You can apply vacuum to the EGR valve and it will open and close easily and will hold. From searching I also know that the 0171 and 0174 are lean codes for the front and back bank. Now, could all these codes be related or do I have two problems going on. Thanks Again.