Someone correct me if I'm wrong but I seem to remember reading in the Haynes manual about there being a special way to bleed the rear valve assembly for the ABS that needed a special tool/equipment.
It could be , even though you bled everything , that there is still air in that valve unit.
The 94 I used to own only had rear wheel ABS.That , I assume is true for your's.
I would pump the brakes a few times and bleed the rears again.
Start from the passenger side.