My '01 7.3L Excursion keeps throwing a low ICP code. Initially I assumed the sensor was bad, and I replaced it, but the code keeps coming back. The truck is sluggish, and there is often a 2-3 second delay when accelerating (this is getting dangerous at intersections). If my injector control pressure is indeed low, what could be causing this?

The truck has a full Banks Powerpack with a 100hp chip. The condition is actually worse when I remove the chip.