The misfiring that I've had a problem with suddenly got much worse today. The car made it in to work without any issues at all, but when I tried to start it to go home, the battery came disconnected (this has happened in the past; a quick re-seating of the negative terminal usually corrects it, and I have an optima battery waiting to go in as soon as I pick up some replacement terminals). After starting the car, I could hear it running incredibly rough, as though it was missing on one cylinder. This cleared up after the car warmed up, but when cruising at highway speeds, it would start up again after a few seconds. By clutching and dropping the engine back to idle, then accellerating again, it would clear up for a few seconds, then repeat the cycle. The problem only manifests itself under cruising conditions; if the car remains under hard accelleration, the car is fine. Time to start diagnosis.