08 TL with trouble codes P0175 & P0172

Hello everyone,
My 08 TL’s check engine light has been giving me a trouble code of P0175 and P0172 for about 5 months now. Its comes on periodically, probably about every 2-3 weeks. I have taken the care to the Acura dealership several times and they are telling me they can’t find a problem. I’ve also have several mechanics check it out and they can not find anything wrong either. They tell me my O2 sensors are fine, the MAP sensor is good and have not found any vacuum leaks. Although they say the O2 sensors are fine I still changed them as well as the PCV Valve and it has improved the car’s acceleration greatly. However, my gas mileage is still terrible at only 18 mpg and the check engine light comes on every so often.
What should be my next move? What could possible be the problem?

Thanks in advance for any help!