I was fighting a similar issue on my 283 that ended up being play in the distributor shaft.

Pulling the cap showed where the rotor was coming up and grinding on it. You might check for play there as well.
Attachments
IMG20231229155949.jpg (167.42 KB, 114 downloads)
Ditributor 1
IMG20231229155952.jpg (170.61 KB, 115 downloads)
Distributor 2
IMG20231229155933.jpg (122.42 KB, 114 downloads)
Cap

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