Shake Shake Shake

What is the idle rpm in the video?
Are you running a ported vacuum advance?
I have seen and heard that intermittent shake before, but I gotta thing a bit.
I think I would do a couple of easy things first, like;
take a look-see in the float bowl looking for fuel contamination. . And I would blow out the idle bleeds right away too, just cuz I'm there. I do this by revving the engine to ~2000, and slamming the choke shut, then releasing it before the engine stalls. I repeat up to three times.
Next would be, as already mentioned, the Strobe test on every wire and a glow-in-the-dark test at the coil. These are the easy things. Here are a few more;
Check your alternator for a fluctuating A/C output, which ain't supposed to be there.
Pull the regulator connector off, and let her run for a bit on battery alone.

This might get to be a toughie, so I agree to find a good baseline first.
As mentioned this starts with a compression test, and a cylinder balance test, possibly followed by a LeakDown test, but maybe not.And the exhaust outlet temp is an easy test too.

I asked about the rpm and timing, because I have seen more than a few times that if the idle is too high, the timing starts darting around, and or the low-speed circuit gets to acting funny. Too much Idle-timing will do that too, and is usually accompanied with a stinky exhaust.
I'm still thinking.

Ok in view of this is going on with multiple carbs I'm going with contaminated fuel, or a faulty ignition , system, possibly the amp.
So disconnect the Vcan and plug the carb -port.
Get the rpm down to something like 650/700.
Then check the timing; 15 will be fine if it stays there until about 1000 rpm, without doing any funny business. Slowly rev it up while watching the timing marks. Stop at 2000, and return to idle..
If the marks do not smoothly advance , but continue to advance only,with rpm, then check your timing chain. But if the sparks drop out or the timing jumps back and forth from advancing to retarding, then your magnetic pick up may be wired in reverse polarity....
or the rotor will need to be properly phased.
Your pick-up should have one Orange wire and NO purple one. The second could be black or gray., but NO purple. If you find a purple wire, get rid of it! or change the polarity. Any Orange wire pick-up off any Mopar engine will be correct. Then retry it. Make sure the ECU case is seeing the same ground that the battery is.
But if the strobe is working properly, stop the engine. Pull off the rocker gear. Take a plastic mallet and bop the heads of every valve, listening for the distintive popping noise they should make. You don't know where the pistons are so don't be wailing on them; a gentle bop is all you need. They should all sound the same. If you previously did a compression test or a cylinder balance test, then pay attention to any oddball cylinders. I do this test with air injected into each cylinder. This pushes the piston down out of the way, and magnifies the popping sound they make. And when you find one that ain't sounding right, it may require a workout to get rid of carbon on the seat. Also, since the piston is gone, you can push the valves down quite far and find a bad spring right away. If you find a spring that you can turn by hand it has to come outta there. At that point I would pull the heads for a rebuild.

I'm still thinking,
but it hasn't come to me yet, I'm old so that's how it goes sometimes. Sometimes I have to hunt around the keyboard to find a certain letter that I just punched maybe in the previous sentence or paragraph. Sometimes the remembrance comes in my sleep or the next day or several days later. Sometimes it never comes, or somebody else comes along with it. Life is grand, then you get old.
Got it! Dirty points is it. That's where I have heard that sound,lol. Mystery solved. Now how does that apply to you? IDK but the first thing I would do is go get a different ECU and sub it in there, with it's case properly grounded. Any Mopar Ecu that fits your plug will do, it don't matter what it's off. Just swap it in, verify it's grounded, and fire it up.