On a hot day OR driving around for a long while running errands and the engine is nice and hot:

The car will start and then dies quickly. As it is dying, I notice the RPM's fluctuating. It won't restart until it cools off.

I have encountered this issue 3-4 times over the past 6 months. But I understand that it gets worse over time. My Accord has 101,500 mi. on it. When it was around 98,000, I took it to the dealer and they replaced the PMG-F1 main relay for free because it was still under warranty( They said they replaced it). This problem did not occur for a while, but last week it resurfaced. I do understand that it is an issue with the fuel system.

IF the pmg-f1 relay was replaced, could it be the fuel pump regulator?

I performed a diagnostic test which I learned from this site. The "3 click test" I call it.
1) Turn ignition to ON - click 1
2)Check engine light goes off - click 2
3)Turn the key to start - click 3

The car started fine. I understand that the main relay will click 3 times before the starting process.

I'm just looking for possibilities if it is not the pmg-f1 relay or any advice. Thanks.