So I was driving my X for the first time in heat (was 90+ degrees) after being tuned in about 65 degrees 8 months ago. My car would not go at a stop light it would hesitate and I would have to press the gas way more than usual to go. Then I saw my Service Engine Soon light go on.

Pulled the codes and got
P0171 Bank 1 System Too Lean - Pending
P0171 Bank 1 System Too Lean - Intermittent
P0171 Bank 1 System Too Lean - Permanent
I looked around the forums and saw that it was either a vacuum leak or my MAF is dirty. So I cleaned my MAF with CRC Mass Air Flow Sensor Cleaner.

*It says not to use on mitsubishi's due to their sensor however there are alot of people including myself that had no issues.

Be careful while doing this sensors are fragile and OEM ones cost about $250.

1. Unplug the Sensor
2. Remove the 2 screws holding it in and remove sensor GENTLY!
3. Place sensor flat on a paper towel
4. Spray the sensor about 8 inches away back and forth. Spray all over until the paper towel is only white and no dirt run off is actively visible.
*You can opt out of using the straw that is provided as too much air pressure can damage components. However I used the straw and had no problems
5. Gently turn it over to the other side and spray it again
6. Wait 3 minutes for sensor to dry and reinstall sensor

After I did this I started my car and hooked up my code reader. Looked and saw that no codes were present. Including the permanent one which WONT be erased by a code reader or unplugging battery for a few minutes and plugging it back in. However the other 2 codes can be removed by a code reader.

Hope this helped anyone with this issue.

Issue happend at 47k miles 2010.

 

Scratch all that and get a better tuner that can properly tune your car.

 

Wasn't a tune issue my MAF was dirty. smh a tune wont clean my MAF

 

My bad, read first part went ADD and got distracted then responded before reading rest lol. I was responding to having odd behavior for a car that was tuned when it got hotter out. Sorry about that!