engine idle goes up and down

There are a number of things, but we need to start with a vacuum leak or throttle body issue.

So first is a vacuum leak.

Here is a guide that will help with this:

https://youtu.be/4ktw1X4W_-k

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

Once we can cross off a vacuum leak, we need to move onto a throttle body issue.

I would suggest starting with cleaning it and seeing if that makes an improvement. Here is a guide on how to do that:

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

Lastly if these do not solve this issue then we need to run through the remaining parts of this guide that talk about surging. Clearly these other causes are part of this so let's run through the rest and then we can go from there.

https://www.2carpros.com/articles/engine-surges

Thanks