Not sure if there's any Duratec to Zetec issues, but I had the same code last summer. After cleaning my TB, I went from too little EGR flow to too much. My fix was to replace the DPFE sensor (like $50 at autozone) and that fixed my problem.

1999 Contour SVT #1966/2760, Silver Frost/Midnight Blue Koni Kit, Mille Miglia MM-S rims, B&M shifter, Stazi mesh, SFCs, optimized Y-pipe & TB, SS break lines, K&N drop-in, Infinity Kappa speakers, MTX amp/sub