Other than a mechanical defect/anomaly as others have mentioned, my money would be on carb ice anyway. In the right conditions this can manifest itself rather quickly. Do you have any idea on temperature/dewpoint at the time and altitude of your flight?
Oh, and another suggestion: water in the fuel? Any chance of that?
Just a reminder but the thread start was
at full throttle With absolutely no warning the power cut to idle.
So that rules out carb icing, , water in the fuel (basic PPL engine knowledge?)
Sticking float valve?