thanks -- don't have the data on the codes yet, but i'm taking it in to another shop, and i'll get them.
it's not a starting issue with the rpm -- just sporadically at idle; only bucking/jerking when attempting to accelerate gently (2000-4000 rpm) without downshifting. when floored, this goes away, but certainly don't have the power i should have; hence the backpressure suspicion.
main cat was all that needed replacing (according to backpressure test performed by mechanic). car ran as good as ever just from replacment of main cat. i fear that the root cause was not taken care of, and thus my cat may be plugged again.
