Rough idle and shuts off when sitting

It is hard to know for sure what you may have missed so the best bet is to start checking things out to find out what is happening then we will know what to chase.

So, we need to find out how long it will keep running. Are you able to keep it running long enough to check for a vacuum leak? Here is a guide that will help with this.

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

If you cannot keep it running, then we need to put a vacuum gauge on it and find out if once it levels out if the needle is staying steady before it cuts off.

Below is a chart that will help with seeing what the issue may be based on the gauge reading.

Let's start with this because I think we will find something with this, and we can go from there.

Thanks