Just had and interesting repair bringing attention to the value of a clean air filter. Not only are you allowing more air to come in to be combusted vs more expensive gasoline but there is the cleaning factor. Have a Nissan which was having trouble idling without any check engine light or codes the engine would idle for a while then just die out on the owner of the vehicle. We found the throttle body dirty and suspecting the Mass Air flow (located behind the air filter and before the throttle) was also dirty we cleaned it with electronic ckt board cleaner. The car idled perfectly on it's own from then on. Needless to say the air fitler was allowing dust and dirt past causing the problem. Just thought I would share this....
Also, for those of you who like to spend the money on those fancy air filters with oil all over them... I've seen quite a few Mass Airflow Sensors and throttle bodies dirty up quickly from these things because the oil can vaporize and get all over the intake tract, which then attracts dust and dirt. A good clean fiber air filter (no oil) will work just fine.
