Have a 2014 Mazda 3 2.0L with 200000 kms. Got a new ob2 scanner today and was seeing the live data, noticed the long term fuel trim was 10.2% short term was perfect at 0 and the MAF sensor was 1.30 -1.50 at idle, I drove it for a while with it plugged in and it went from 7.3-11% on the long term. Seems to run fine, besides a little vibration at idle, but it did that since I bought and had 0% LTFT back then. Sensor and throttle body are clean, I put injector cleaner in about a month ago so don't think they are clogged. And 0 codes.
The MAF sensor reading is off. It should not read negative values.
The maf reading wasn't negative 1.50 I meant the lowest at idle was 1.30 and the highest at idle was 1.50. sorry for the confusion
When the engine warmed up, put the car in drive and while idling, report the MAF sensor reading and all the fuel trims. Make sure all the accessories are off.