Engine bucks, jerks and revs on its own

More than likely, we have an issue with the air fuel ratio. This means we either have a fuel delivery issue or unmetered air coming in.

I would suggest starting with the basics. Let's check the fuel pressure and for a vacuum leak. Here are guides that will help with both of these:

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

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

The next thing we need to check is if there are any codes and then monitor the o2 sensor data. This is going to need the use of a scan tool.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

I am attaching a chart below that will help with reading the short-term fuel trims. This will tell us if we are dealing with what I am suggesting. Basically, it will show the exhaust is lean and this will show that we need to find where the addition air or lack of fuel is coming from

Please let us know what you find with this, and we can go from there. Thanks