slanty surges at stops?

The last week or so I've noticed the ol' girl hasn't been enjoying coming to stoplights and all that. The car drives perfect, and it idles and park and neutral just fine. But idling in gear at a stop or something causes sputtering, missing, and eventually, stalling. Usually it doesn't happen until the car is warmed up good.

A mechanic was looking at it a few weeks ago for an unrelated ignition issue and he told me the carb gasket wasn't any good. Could it be possible I've got a poor seal there? Would that cause what I'm experiencing?

TIA