Ditto on "clean the MAF". Meanwhile, it'll re-trigger the CEL during higher loads on the engine. You have to carefully but thoroughly clean those fragile wires that are way down inside the sensor itself. See the link above.

Also that same P0171 or P0172 code can be caused by leaky TRD headers when their crummy gaskets fall apart after a year or two and cause a header leak. They now use a different type of gasket, plus I used lots of gasket maker to help hold the new rubber gaskets in place. If you don't have TRD headers, you can obviously ignore that suggestion.