Engine starts and stalls after engine has run but sits for 15 minutes?

2000 Honda accord v-6 Heat soak issues. Engine starts and then stalls.Car starts fine when cold. Runs fine unless you let it sit for about 15 minutes then it stalls engine check light comes on. OBDII indicates all cylinder missing code 301 -306. I'm told the alcohol in winter blend fuel here in Calif is the problem as it boils and creates a vapor lock in the fuel rail. What is the cure will just replacing the Fuel pressure regulator with a 53 lb unit correct it or must the ECU be replaced also?

You're going down the wrong path. Don't assume it's the gas, think, there are 40 million people using this gas and they don't put new FPR's in their cars.
The higher rail pressure will make the car run rich, wash down cylinder walls and suck for mileage. Get the car diagnosed properly and stop guessing
The engine starts well when it's cold because the computer always runs the engine rich on start up when it sees a stone cold measurement from the coolant sensor. When you start it hot that extra rich mixture isn't there to cover up possible vacuum leaks or stuck EGR valve, or a cracked air intake hose.
The ECU is the last thing I'd even consider.

Vapor lock went out when electronic fuel injection came in. In the old days the fuel was not returned to tank like the systems in today's cars do so tell the person or persons they don't know what there talking about and I don't care if it is all alcohol in the system. Work on the misfiring stop listening to fools. And if you would like to put a fuel pressure regulator on that is above the spec for the engine you will be causing more problems so don't loose this website your going to need it.