The number one symptom of eroded away spark plugs, overdue on being changed, is rough idle and stalling at idle when coming to a stop.
Like several have posted already, check your O.M. if you're overdue for a spark plug change, then that is the first place to start and will likely solve your problem.
Some years of Commanders engines had ignition cables, some had purely coils over the plugs. If you've got cables, they often degrade and hurt the ignition as well, more than 100k on the cables, I'd consider changing them. When you change the plugs, inspect the boots any damage replace them.