Codes P0300, P0301, and P306?

Hi,

It could be a couple of things. Since you have already replaced the plugs and coils, you may want to check the fuel pressure to see if it is weak.

Here is a link that explains how it's done:

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

If the same codes return after clearing them, you may want to consider checking engine compression. Low compression in a cylinder or cylinders can also cause a misfire.

Here is a link that explains how that is done:

https://www.2carpros.com/articles/how-to-test-engine-compression

Both of these tests require a pressure gauge. Most parts stores will lend one to you free of charge.

Let me know your thoughts. Also, if you have other questions, let me know.

Take care,

joe