The next thing I would check would be compression and the fuel injector for cyl 3. It may be stuck or not operating. Also, low compression will cause a misfire as well.
Here are a couple of links to help. The first explains how to check an injector.
When checking the injector, make sure it is getting a pulse (power) to fire.
Here is a link showing how to check engine compression:
Try these things and let me know the results. Also, let me know if you have other questions.
Take care and God Bless.
Monday, February 22nd, 2021 AT 6:54 PM