I cant view the vid just yet (at work) but I will look over the weekend. Just for the hell of it, have you disconnected and plugged all ports on carb? or eliminated vacuum leaks? How are the power brakes? Power brake boosters can leak vacuum. For the sake of saving time have you swapped the carburetor just to see if it does anything dififerent? although you said it did the same thing with a two barrel corrrect? Like said isolate the carb remove hoses and plug all vacuum ports see if there is a difference. the fuel fliter,yes id set it up vertical, but I have ran them similar also with no issue.
