Sputters and shuts off after reaching operating temperature

Hello,

This sounds like vacuum leak. To be sure here is a guide to help you check:

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

Can you please shoot a quick video with your phone so we can see what's going on? that would be great. You can upload it here with your response.

Please run down this guide and report back.