A method of controlling a diesel engine connected to a load, the method including the steps of detecting an increased torque requirement and matching a fuel flow with an airflow. The detecting an increased torque requirement step detects an increased torque requirement for the engine, the increased torque requirement taking place during a period of time. The matching a fuel flow step matches a fuel flow with an airflow going to the engine during the increased torque requirement, the matching step keeps the airflow and the fuel flow during the period of time at a substantially stoichiometric level enabling the use of a three-way catalyst to reduce NOx emissions during transients.