What kinda shop did you take it to, a simple internet search comes up with.
Common Problems That Trigger the P0171 Code
Control module software needs to be updated
Vacuum leaks (intake manifold gaskets, vacuum hoses, PCV hoses, etc.)
Mass air flow sensor
Plugged fuel filter or weak fuel pump
Plugged or dirty fuel injectors
Common Misdiagnosis for the P0171 code
Oxygen sensors
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GTR TT 493Whp/431lbft, Ecutek, Southbend 6puck,Quaife, RPM RollBar 4Point, R888R, JRZ RSPro F(10R/10C) R(10R/6C) 1000f500r inlbs+150inlbs Tender, SPL everywhere.
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