454 Chevy

Maybe the in-tank fuel pump is starting to fail. Check fuel pressure when cold and when hot.

What year-- several different fuel systems used over the years?

I could have guessed your alternator has nothing to do with a 454 running badly.
Do a 'search' for 454 and you'll find a thread or two (well, I did) which might give you some help with your problem. Notice the comments about collapsed vacuum lines and distributor advance mechanisms. Don't discount the comments here about a failing fuel pump.

Sounds more like a clogged fuel filter to me..

check the exhuast system.....the cat converter could be clogging up when it hot....

Really need the year of the 454 carburetor, throttle body, port injected?

Just to many possibilities with out more information.

My 454 carburerated has a fuel filter in the carb. Check that first.
Second 454s are notorious for collapsing the vacuum line to the distributor for vacuum advance.
My 454 was running like sh-t and my mechanic did all the vacuum lines. What a difference the truck runs great. Before I could hardly get up a hill.

Try these 2 simple cures first

I agree with the fuel filter issue, when the vehicle sits during a hot soak, it actually gets warmer as no air flow is going through the radiator, that can make fuel boil up to the carburetor or fuel injection thus making your vehicle run correctly. I would change the fuel filter first. Good luck.

Bob

We may be solving this by ourselves... for ourselves!
:W

Mr. Dan wrote:
We may be solving this by ourselves... for ourselves!
:W

LOL! I used to Mod a guitar forum... Happens all the time. Post and run! :B