I have since gotten hold of the car and some clarification. The "jerk" was a sudden, split second loss of power (similar to an engine dying mid drive). The fuel pump was not activating, so I replaced it. Now there is fuel pressure at the motor (though very little) and her fuel pump fuse and relay are both intact/functional. It recently received new spark plugs and an oil change.
When the key is turned, all of the electrical components come to life as normal and the engine will turn over but not fire. To me this means no air, fuel, or spark. However, I am stumped and seem to have hit a wall in my troubleshooting. Any ideas/help etc is greatly appreciated.
The car has a problem where the thermostat goes bad about once a year. The car will overheat, not have heat and have a severe loss of power after a short time. Swap the thermostat and it is good as new for another year and a half +. Otherwise the car runs like a dream.