Had something similar recently. Checked all the usual stuff as mentioned above. Took intake off countless times. Inspecting everything. Ended up being the pin inside the injector plug wasnt contacting the injector pin very well.. Looked good on the visual inspection. Injector would work most of the time. But other times it would hardly be firing or not at all. With only one injector per rotor. Makes a big difference how it runs. Next time it does it get a mechanic stethoscope. Put the probe on each injector.

 

Thanks - I'll carry one with me on the next test run.