Did you change the PLUGS
I found the front ones need changing early 0.70 on front bank after 56,000 miles !!!!
Just do the front if your mileage is similar
The rears were OK 0.63 !!!!
1999 GREEN Contour SE SPORT Duratec V6, ATX, SUNROOF, 93,000 Miles, P0420 ON&OFF -replaced DS O2 --did not FIX
*New TORQUE CONVERTER @ 53,000-Intermittent P1744
*New DASH at 53,000 and New DASH lifted-now using MOLLEY bolts to pull down
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