My 4Runner has a check engine light code p0171, my MAF is relitively new from a wrecker and I clean it periodically, I used throttle body cleaner to try to find a vacuum leak couldn't find anything, replaced the front o2 sensor still get the code also my 4Runners idles up when I coast to a stop sort of surging I'm not sure what to do,I ordered a second 02 sensor for the back, should I try the fuel pump or injectors? It is a 99 4Runner engine that I swapped into my 90 4Runner thanks for anyhelp!
As you may know, his code is related to a lean fuel condition which is normally related to many of the items you have listed. I would recommend checking the injector pulses to be sure they are providing enough fuel to the motor. Often times bad injectors can also cause a lean fuel mixture.
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