RPM's jump up and down

I would suggest starting to check for vacuum leaks. There are a number of things that can cause this so let us know what you have done so far. If nothing then I would follow this guide first and let us know what you find and we can go from there.

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

Once we know this we can move on. I attached another guide that talks about high idle which is slightly different but contains things that we will need to run through if there are no vacuum leaks.

https://www.2carpros.com/articles/engine-idles-too-high

Okay. Let's move onto fuel pressure. Here is a guide for that. We need to see what the fuel pressure is doing when this RPM is ranging like this.

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

If you don't have a gauge then you can probably rent one from a parts store. Let me know if you have questions.