desert sand is quite hard on air filter and everything behind
I use CRC MAf cleaner from ACE , disconnect MAF and clean them with the spray . I also clean air filter box, connections, MAf to throttle boyn pipe.
Its also a good ptacrice to clean up the throttle body with a carb cleaner ( everything is disconnected so its a easy 10 min job )
if you want to be sure about the maf just disconnect the MAF plug and disconnect bataery to reset ECU and see what happens