I get or had PO171 for a long time.
I have cleaned the MAF several times. Replaced the upstream O2 sensor twice. Replaced several vacuum lines. Replaced the air filter. ECT, IAT, MAF both O2 sensors are working correctly.
This past week I replaced all the injector O rings because they were leaking air on the intake stroke.
So far I'm at 270 miles at about 1/4 tank left.
For me the code comes and goes every 6 weeks or so about every 1100 miles, it appears while accelerating up to 70 or so, or while crusing at 70 or so, it has never came on during city driving.
Anyways good luck with your code it has been nothing but a massive headache for me since August.
