Car sluggish and jerky in only first gear
Among the possibilities are faults in the throttle position sensor (https://www.yourmechanic.com/services/throttle-position-sensor-replacement), mass airflow sensor (https://www.yourmechanic.com/services/mass-airflow-sensor-replacement), vacuum leaks, a clogged fuel filter, defective EGR valve or control circuit, and worn out spark plugs and wires. A mechanic would simply investigate these...