gtr misfire that won't stay still

[yanay]

93 rb26dett pretty stock with red super spark coilpacks and new coilpack harness, new NGK iridium plugs and new stock injectors, swapped ignitors, mafs have been inspected and cleaned. Compression check was good (161-170) timing adjusted to 20 degrees. It had a misfire at idle (1300 rpm) constantly backfiring and no change when cylinder 4,5,6 are unplugged but when mafs are unplugged the misfire moves to cylinders 1,2,3. I can't track down what is causing it. Mafs are the next things to get replaced I think but can't afford chasing it by replacing parts