Hello everyone! New member here hoping to get some insight on an issue with my 1997 Honda Accord V6. It’s the C27a 2.7 V6 engine with about 255,000 miles. I know it’s not the preferred motor for accord guys but it has a sentimental value as my grandfather bought it new in 97 and been in my family since day one.

So, the car sat for about 15 months while I was away from home and when I got back I wanted to fix it up and get it road ready again hoping to make it my DD. Before it was parked it ran perfectly and was driven daily out of town.
I replaced a lot of parts hoping to keep it running for awhile longer. I’ve never had any problems out of this car other than regular maintenance.
My problem now is that when the engine is hot (like it’s been driven) in order to start the engine again, it cranks for 10-15 seconds. If I start the engine within a couple minutes it’s fine but if it sits for 10 minutes or more it will crank for awhile before it starts. If it sits overnight it fires right up. It also idles fine even if it’s acting up while driving it. After driving it awhile at operating temperature, the engine will sputter and significantly lose power like it’s about to die. When this is happening it seems random but the longer it runs the more frequently it happens. It also has to be driven for some time before it starts doing this.
Another related symptom is that when the engine is sputtering, sometimes it will stall when coming to a stop. As of now it hasn’t stalled while driving at highway speed, just when coming to a stop and it only stalls sometimes. I’ve always been able to just start it right back up and continue home.
I originally thought it was a fuel delivery issue and I ended up taking it to the local Honda dealer hoping they could figure out what was going on and I would just over pay to fix the problem.
I told them I thought maybe the fuel pump was going bad since it sat for so long and they tested fuel pressure and seemed pretty confident it was not the fuel pump. After 4 days they ended up replacing the main fuel pump relay even though I already replaced it with a part from Amazon. Still having the same problem and the dealer told me they would just have to keep replacing parts till they find the problem.
I have driven the car about 1000mi with this issue and it will not throw a CEL code.
A list of parts I’ve replaced and things I’ve done so far:
-Spark plugs and Wires
-Ignition Coil
-Distributor cap and rotor
-Battery
​​​​​-Fuel pressure regulator
​​​​​​-Cleaned throttle body and IACV
-Fuel filter
-Main fuel pump relay
-Professional fuel system cleaner (from a shop)
-Pour in tank fuel system cleaner
-Coolant temperature sensor
-Air filter
-Checked for any vacuum leaks
-Also not very relevant but ALL the fluids were changed and had a new cat back exhaust installed.

Before I replace the fuel pump and just hope that’s the problem, I was hoping someone may have some insight on anything that could be causing the car to do this. I’ve read online maybe the crank position sensor but also people say it will throw a CEL usually for the crank sensor. I also don’t think a sensor would go bad from sitting, that’s why I’ve leaned toward a fuel delivery problem. Thank you for reading this far and any suggestions will be greatly appreciated!