No power, misfires, rough idle and code P0300

Hi,

The code is a random misfire. It could be several things causing it. Lets start simple. First, check to make sure there are no engine vacuum leaks. Here is a link that shows how it's done:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Check to make sure none of the vacuum hoses are disconnected, cracked, or broken.

Also, take a look through this link and let me know if it helps.

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

Let me know if that is the only code you have and if anything sounds differently.

Take care,
Joe

With a multi cylinder misfire we need to start with things that can effect the entire engine. Basically what this code is saying is one cylinder misfires then it does not and then it starts again and that multiple cylinders are doing this. So there is no one consistent misfire. That means it is normally air or fuel. Let's start with these two guides to try and figure out if you have a vacuum leak or fuel pressure issue.

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

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Let me know what the pressure is and then we can go from there and if you find no vacuum leak then we can move on but I suspect based on what is happening that we will have an issue with one of these. Thanks