[Gaz64]

After watching your video many times, I can't see the misfire being anything else other than an intermittent ignition misfire.

It occurs a various rpms and loads.

I had a set of Autolites in mine a few years ago, went hard for 300 km, then had intermittent miss, one spark plug faulty.

Generally the mixtures are too rich, have you got any photos of the spark plugs when they were out last?

Gary