I have a 97, f150, long bed, reg cab, 6 cyl. Last year I had a "junk yard" engine installed (old one had a cracked block). I initailly got 16mpg. Then it started dropping. I now get 8-10mpg regardless of driving conditions. I was getting codes po171 and po174. Here's what I have done: new plugs and wires (twice), new coil pack, new fuel injectors, new egr, new pcv and pvc tube, new fuel filter and system flush, cleaned maf sensor, coolant flush, 4 new tires. CEL's are off now. I need to get at least 3 more years out of this truck. I am probably into this about $4000.00 . Any help/ideas.

 

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