Looking at toyodiy.com, the JDM loom/ecu combination didn't use a resistor pack, however the ADM loom/ecu combination did. Based on that I would say that you don't need a resistor pack, but if you want one I've got a spare. Also, I would expect that not having a resistor would burn out the injectors rather than limiting the engine to 4000rpm.
Is it possible that you've got an incompatible dissy/ignitor/ecu combination? Combing ESA and VAST components would cause timing issues that may have the symptoms you describe.