Well, after over 1000 miles of trouble-free driving the P0171 code came back. However, by the time it did, I had read so much about P0171's that it didn't stand a chance! With the aid of several of you and a handy can of rake cleaner, I found 2 injectors sucking air. Now it's time to replace the O-rings on all the injectors so I need some more advice. What type of lube should I use on the O-rings?