Shake Shake Shake

Man that's weird, sounds like it's still "surging" a bit in that last video while you were standing at the back of the car. You said in the first post you've already messed around with the carb/tried others, did you tune the idle mixture for max manifold vacuum? The engine in my Duster has a more radical idle than yours but I was able to get it pretty smooth to where it doesn't want to surge up and down, I'd think that should be possible with your combo as well...

Or just ignore it lol, if you know the engine isn't hurt internally and you've said it runs well.