stuttering gets worse when defrost is on?

Yep, when the engine is under load it will misfire because this is when the ignition system is under stress. I would do a full tune up with spark plugs and ignition coils with are a common failure, also I would service the throttle bore, here are two guides to help walk you through the repair and instructions for your car in the images below.

https://www.2carpros.com/articles/how-to-tune-up-a-car-engine

and

https://www.2carpros.com/articles/throttle-actuator-service

2.0L 4-cylinder (4B11) NGK ILKR7E6 (Iridium) 0.039 - 0.043 in (1.0 - 1.1 mm)
2.4L 4-cylinder (4B12) NGK ILKR7B8 (Iridium) 0.039 - 0.043 in (1.0 - 1.1 mm)

Check out the images (below). Please upload pictures or videos in your response of any problems so we can see what to help you with.

Thank you so much.
I figured it needed a tune up.
In my state a full tune up can be expensive.
I will have them focus on spark plugs and coils .

Sounds good, I would have them do the throttle bore service as well.