If its under load then its either too small a spark (dwell time, plug choice, etc) OR a lack of fuel, which might indeed be that the injectors are doing something funny at a larger duty. The ignition issue would feel like a missfire, a "brrrrr" sound as it tries to boost, maybe dropping onto 3 pots or less. If it was an injector issue you'd expect to see it go lean as dave says before you actually feel the missfire.
Did you ever get a log of the fault ?
What ECU do you use ? If you want to send me the file I'll look over it for you, probably won't see anything that AVA havn't seen, but you never know