Thanks to Framos and Crimpton for your input. I finally had some time to look into my problem tonight. I cleaned the MAF sensor and the throttle body. Cleaned it really well...started it up, and it ran like it used to...smooth. The real test will be tomorrow, but I'm confident that the problem is gone (for now). This website http://www.obd-codes.com/trouble_codes/generic/p0171-system-too-lean-bank-1-oxygen-sensor.php
had info and possible causes for the code. This info helped to reinforce what you guys told me.

The main website page http://www.obd-codes.com/trouble_codes/ has code information on GM, Ford, and Subaru vehicles.
Thanks a bunch