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the 171 code is a lean code. possible causes are
1. vacuum leak
2. mass air flow sensor
3. pcv valve
4. low fuel presure
I see they have checked some of these items. cleaning a mass air flow sensor never works. the carbon is baked on the element and no cleaner can take it off. this is monitored by looking at long term trim for bank 1.
do you have a scan tool to be able to help track down the failure???
a scan tool to monitor all sensors.
do you still need help