Engine "stumble"

[Mike Koolhof]

Hello all!
My 77 4x4 has what feels like a miss. I have replaced plugs, wires, distributor cap rotor and coil, vacuum advance module, fuel filter. It starts and idles fine. Only happens when I'm going down the road. Seems to have plenty of power, just all of a sudden gets what feels like a miss.
Any suggestions greatly appreciated!

 

[bucket]

How often does it do it? Does the issue go away if you give it more throttle?

 

[Doppleganger]

I have something similar ATM - does it sound like its dropping 50-100rpms for just a second? This happened to me after a carb swap and although you can feel it under throttle, is more noticeable at idle.