Reminds me of a light twin that I used to fly quite regularly that had an engine failure at night (someone else flying) - followed by a gear indication issue necessitating an assymetric go-around - followed by a successful landing. The next day the pilot checked in with the LAME working on the aircraft; the LAME said "we found the reason for the failure ... blocked carb jets". It was about that time that the pilot informed him that that was the engine that was still working ...

Turned out to be a fuel contamination issue from the aircraft being refulled from 44 gallon drums at a strip somewhere; why the aircraft was not required to have a fuel filter I will never know.

Interestingly, I had an instructor turn off the fuel to the left engine as part of my BFR; I was quite surprised at how long and gradual the decline in power was ... not abrupt at all.