Replaced all my accessory bushings (think there were 5 or 7) two years ago. I notice a little sag in them, but not too much.
I had not thought of a bent pulley, thanks for the idea.
I think the easiest thing to do is pull the belt off the alternator and run without it for ten minutes. That way I can see if the intermittent "miss" is related to the alternator.

plugs and wires are newish and this has persisted for a long time. Dizzy cap and rotor are new as of this summer.

The belt motion is the same as this alternator was doing before I had it rebuilt - as though it has bad bearings. But I had those replaced....

Thanks and happy new year,
Will
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1990 740 Turbo, on its way to stock specs, maybe beyond