[DD716TED]

I live in a new manufactured home (6 years old).. We have a dust problem that I cannot solve... No matter what we do, the house gets dusty within a day or two of cleaning... The house is heated electrically and with the assistance of a heat pump. These have all been cleaned.. The vents have been cleaned, furnace filters replaced each month, additional filters placed on the underside of the floor registers, windows and doors checked for air leaks, and the dryer external vent connection checked... we still get dust..
Additionally the carpets have been cleaned and vacuumed weekly, all bedding (mattersses / comforters) cleaned and furniture vacuumed regularly... still dust... I cannot think of anything else to check.. has anybody experienced anything similiar to this and if so, what was your solution? The only thing that I have noticed since moving in was that last winter when I cut a hole in a wall to move a power outlet, I experienced a real draft of cold outside air coming out of the hole.. don't know where it was coming from as a mfg house is built on top of a subfloor which should be airtight.. maybe it was coming from the attic through the wall which is naturally vented to the roof but then again the walls should be framed so they are not open to the attic ... I don't know?