You indicated noise when starting resembling valve rattle. Is the engine oil clean and full? Next, you had it tested at Auto Zone. Was the check engine light staying on when the engine was on? If so, did they happen to tell you if there were diagnostic trouble codes and what they were?
As far as an ignition coil, chances are you would have had a cylinder misfire code. However, please keep in mind there are many things that can cause a rough start and a stall at idle. Here is a link that explains in general the most common causes of a stall at idle.
Let me know. Also, if it's possible, record the engine starting so I can hear what you described.
Saturday, December 28th, 2019 AT 10:20 PM