If transmission has never been serviced, you need to have the bands done and also fluid change. The clutch bearings could be an issue. However, check your wiring, have you ever changed spark plug and other critical wires? If not, better get all the critical wires cvhanged. Also, what about the emissions? PVC Valve must be changed periodically, also, is the cvatalyc converter plugged up? If so it will cause car to jerk vioilently when warmed up. Converter can glow red hot when plugged and cause a fire or explosion.
It depends when it jerks... Does it jerk for each time you accelerate per gear? Does it jerk on initial acceleration? When was the last time you changed the transmission fluid? It can also be the gear box.