I have tried forever to get rid of it with little success. My most recent attempt was by adding Nistune and I have made it 60% go away through tuning and I have small hopes I can get it 90% gone. The idle has always been rough; I have smoothed it out a bit through tuning. That said I would probably be in a better position had I just sold the injectors, bought Nismos, and went with another premade tune than to buy Nistune and trying tuning them.
I have a wideband and when the k-value is good for driving around AFR's, the idle AFR's are too lean like you acknowledged. I cannot find a happy medium.
DW injectors seem to be a complete hit or miss with half having no issues and the other half have nonstop issues.
Once I am out of college and have some extra money I have EVERY intention to switch out these injectors for Nismo.