Engin error light code indicates engine running lean. on 2002 Mazda Protege

Where do I find what should be checked and in what order. Also, what would the cost range be for repair shop fixing problem?

Asked by for the 2002 Mazda Protege
Here's some info on the p0174 and p0171 codes that normally occur when the engine is running lean:
A shop will likely charge about an hour of labor to diagnose this, maybe less but maybe more, depending on the difficulty in finding the problem.