kevin,
yes i have seen this same issue on trucks with this system on it. They had issues with the injector like this... we tried cleaning them but usually we wound up replacing the injector because of comtamination. One other thing that came to mind was inside the injector body underneath the pressure sensor some of them had a thin mesh filter screen that could get clogged up as well, we were instructed to replace that as well. If yours has one i'd replace that too next chance you get if yours has they type of sensor on it.