Be careful doing this, it can shock you. But here's what I would do.

It sounds like you have multiple missing cylinders vs having timing issues. This can be caused by an out of round distributor shaft, broken distributor cap, or bad wires.

While the engine is running, use long-nose needle nose pliers that the metal portion of is grounded to the body (with a long copper wire), and pull the wires off the distributor cap (NEVER off the spark plug!). Pull a wire off and see if the engine tone/rpm changes. Put the wire back on, of course, before going to the next. I assume you've ruled out all 8 injectors (all fire) as a possible cause, so this is the next logical step. What you describe sounds as multiple cylinders missing, and you can muck with timing and dwell, but if you have 2 or 3 cylinders missing you'll have rough running and a lot less power. The 4.5 can run with only 3 or 4 of the 8 cylinders actually firing.

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2021 Charger Scat Pack Widebody "Sinabee"
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1972 280SE 4.5
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