The P0100 indicates a problem with the air flow sensor readings. There's a recall on this car (if it's a U.S. model) regarding the air flow sensor connector (and reprogramming the ECM if it's a V6). Call your local dealer with vin in hand to see if there are any uncompleted recalls. If recall 039 is open, having it done could remedy your problem. If it's already been completed, check the hose between the air flow sensor and the engine and verify it's on and secure and has no openings. Also check the mass air flow sensor connector for good contact, meaning the air flow sensor pins must fit snugly into the terminals in the connector. Sometimes the female terminals in the connector push apart and don't always make contact with the sensor terminals. This can often be remedied by twisting the pins on the sensor (just a little) and reconnecting the harness. If all that is okay and you still have the issue, then you probably need a new air flow sensor. There are still other possibilities, but the likelihood is very small compared to the items I've mentioned above.
P0442 indicates a small evaporative emissions leak. It could have been caused by an improperly or incompletely installed fuel cap, or by an actual problem in the system. If I didn't have the diagnostic equipment I have, I'd make sure the cap is on correctly and clear the code and see if it returns.