Check engine light does not turn on

Hello,

Please elaborate a little more on the issue.
What do you mean when you say the engine is performing poorly?
Does it run rough? Does it have low power output?
Dies it hesitate on acceleration.
Poor fuel mileage?

An engine can hesitate on acceleration or run rough due to a number of reasons.
It could be due to a weak fuel pump, worn spark plugs, dirty mass air flow sensor, dirty fuel filter etc.

Here is a helpful guide:

https://www.2carpros.com/articles/engine-hesitates

Let me know more details about what you are experiencing.
Thank you.