Ah, that makes much, much more sense. Thank you.
Those codes indicate that the fuel mixture in the engine is lean. There are various possible causes for this, but don't replace oxygen sensors or anything else. What this needs is some diagnosis.
Common causes: any vacuum leak needs to be repaired. You can have broken vacuum lines, or there could be a vacuum leak at the intake manifold gasket, but there are ways of determining where the leak is. If there are no vacuum leaks and the condition is verifiable (using a special handheld computer, the mechanic can see that the condition is present), the most common fix for this is a faulty mass air flow sensor, or MAF sensor.
MAF sensors are expensive, and I don't want you to just run out and get one. This really needs a quality diagnosis, and there's no way you should be forced to spend $350 just to find out. This will take a good, qualified mechanic no more than an hour to sort out, so my best advice here is to get a second opinion from a reputable repair shop. Avoid chain stores, like Midas or Sears, you need a good local shop that has a reputation for expertise and quality. I diagnose these issues on a regular basis, and I would never dream of telling a customer that I need $350 just to tell them what's wrong.