Oooh, oooh! That sounds just like when my ignition coil went bad. Car was
warmed up and had been zipping down the road when the power all went away.
Push in the clutch and expected it to die but just goes to idle. Then seems
to run fine again for a while before the problem happens again.
It did it once and then didn't do it again until two weeks or so later and
then happened again and gradually became more frequent.
Does this sound like your problem? Replacing the coil fixed it for me.