Digital BW, The Print

I have developed a BO workflow that looks great on EEM.  I use an 
Epson 2200 and the standard inks (hate the Eboni).

I find PhotoRag significantly more beautiful than EEM, but using BO, 
I get a streaking problem: especially in the darker areas, there are 
repeating strips of lighter density going in the same direction as 
the print heads.  This is not a clogged-head problem-- the streaks 
are wider and more vague than you'd see in that situation.  It looks 
as if you took a 1/2 inch-wide eraser and lightly drew it across the 
page again and again, but with varying force each time. 

I've tried using different profiles, etc. but always the streaking on 
PR.  When I do full-color BW there is no streaking on PR, and when I 
use EEM the BO approach works fine.  Anyone else seen this and found 
a solution?  Ideally I would like to do all my BO printing on PR.  
Thanks.