[manicmechanix]

I wanted to throw a wild guess out there. Do you think the reason you are seeing wider EGR duty if you really are, might be because the PCM is compensating for the lower back pressure exhaust you have on it when does its I/M readiness testing? I'm not sure if the system has that kind of capability or not to tell you the truth. Anyway, if it were compensating it wouldn't affect the engine running bad problem you are having, just possible create wider duty cycles, unless they are fixed.