I also have a P0171 and P0174. Symptoms are a rough idle when I start up the car on cold (less than 30 degree) days. Sometimes the car will stall out a few seconds after I start it up.
Last night I sprayed carb cleaner on all of the engine seals and hose connections and found that the upper intake manifold (UIM) gaskets were shot.
You might want to check your UIM gaskets, since a bunch of us seem to be having the same problem.
96 Contour SE
Duratec V6 24-valve 2.5L ATX
108,000 mi.
Replaced: crankshaft w/ DMD, EGR valve (clogged), EVR, DPFE, PCV valve, evap emissions hose & tube (cracked), window regulator (broken), LH & RH PCV tubes, UIM gasket (leak), ignition coil
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