Built in safety function to prevent engine from running lean and your MaxxECU settings has been triggered, aka engine runs lean based on your tune, see lean power cut settings.
•Lambda sensor is broken. Check your logfile using either the Live-logger or the Built-in Logger.
•Your engine runs lean based on the conditions in MTune. Check fuel pump, filters, injectors to make sure no mechanical issue. <-- most common problem.
•Your boost is running outside the tuned area.