What is a common result of over-throttling an engine?

Over-throttling an engine can lead to a loss of power due to excessive fuel and air entering the engine, which can cause a condition known as "running rich." In this state, there’s more fuel than the engine can efficiently combust, resulting in incomplete combustion, an increase in engine load, and consequently, a decrease in power output. This situation can overwhelm the engine's capability to process the fuel-air mixture effectively, thereby reducing overall engine performance.

In contrast, options such as improved fuel efficiency, enhanced acceleration, and better handling do not logically align with the effects of over-throttling. Typically, one might expect fuel efficiency to decrease under these conditions, while acceleration and handling are often worsened due to the reduced power and potential issues with engine responsiveness.