Final answer:
The symptom of slow return to idle with no DTCs can result in excessive fuel consumption (Option 2) and a lack of power (Option 3).
Step-by-step explanation:
The symptom of a slow return to idle with no DTCs (Diagnostic Trouble Codes) can be excessive fuel consumption. When the engine isn't returning to idle properly, it may continue to consume more fuel than necessary, resulting in poor fuel efficiency. This symptom could be caused by a malfunctioning throttle body, idle air control valve, or other related components.
In some cases, a lack of power may also be observed as a symptom of slow return to idle. When the engine doesn't return to idle smoothly, it may struggle to produce the necessary power, leading to a lack of acceleration or reduced overall performance.
Therefore, the correct answer to the question is option 2) Excessive fuel consumption, and option 3) Lack of power.