> But even having more than one cup of decaf brings on the shakes and skipped beats. The caffeine microdosing adds up, I guess.

You may have a problem other than a caffeine addiction. Cutting out caffeine may be the easiest/cheapest way to address it, but it is not normal or healthy for a few mg of caffeine to give you jitters or affect your heartbeat.

I'd talk to a cardiologist to make sure you're not just hiding the symptoms of a life-threatening problem.