Hi and thanks for using 2CarPros.
Based on your description, I think you have a vacuum leak at the power brake booster or the check valve.
Try this. Disconnect the vacuum hose to the power brake booster and plug the engine side vacuum. Start it and see if it idles properly. Keep in mind, you will not have power assist to the brakes, so I would not drive it.
Let me know what happens.
Wednesday, December 5th, 2018 AT 7:23 PM