Here's a link to the issues associated with a P0174 code:
There's a bit of a punch list of stuff that could be causing this code. If you have never changed the O2 sensors on this car that is where I would start; replace all of them. Get OEM exact replacements versus "universal" fit O2 sensors.
The Mass Airflow Sensor (MAF) may be dirty. There is specially formulated cleaner for removing any built up mung on the sensor.
The PCV system can be checked for proper flow. Replace the PCV and/or clean the system if there is no valve.
Bring the car in and have the injectors professionally cleaned.
You're probably in the neighborhood of 165-170K. If you've never done any preventive or regular maintenance then there could be a lot of issues with your car. The P0174 is a lean condition. It could be bogus inputs to the engine management computer (via bad O2 sensors and/or a dirty or bogus MAF sensor). It could be really dirty injectors because they've never been cleaned and if you've been filling up with non-top tier fuel (because you're saving 2 cents a gallon) then it's a sure bet the injectors are dirty. Running lean comes from air leaks into the manifold post MAF sensor. This could be from rotted vacuum hoses or cracked/broken vacuum fittings. There's just too many possibilities to be able to nail it down for sure. Use the link and the info there to start your trouble shooting.