I was caught up in the middle of the haboob (major dust storm) in Phoenix this summer. I drove through it in my 2008 BMW X3 (40K miles) for about 45 minutes. Ever since, the engine has been idling rough and hesitant on acceleration. I had replaced the air filter which was full of fine dust particles and thoroughly cleaned and vacuumed the internal of the filter housing. I also used Chevron Techron fuel system cleaner on a couple of tanks. The condition has improved a bit but it is still not back to how it was before. Would appreciate any other suggestions short of taking the engine apart. Thanks.
Don’t forget to clean the mass air flow sensor.
or google dust in mass air flow sensor. There are many links on how to do this.
Also look into your air filter box to see if there’s a sound dampening filter beyond the air filter. I had one built into my tC airbox, and that could get clogged as well.