88 Chevy 454 motor issue

What coach is this?

I had the exact thing happen on a 85 Pace Arrow.... Push the pedal and it sits there.. Sometimes you can nurse power by feathering the pedal a few times.

I rebuilt the carb, changed BOTH fuel filters (did you?), vacuum lines, etc. The problem turned out to be a cracked brass female 1/2" pipe to barb hose adapter that was sucking air. On the Pace, and probably Southwind, there are two of these at either end of this 20'+ fuel pipe.

Check for a fuel filter at the inlet line to the carb. They can give you problems if they are plugged.
BTC

Does it have a plastic snorkel on the air cleaner. They can collapse when they get warm.

Thank you for all your help. It's in a Gulfstream SunSport.

Also be suspect of the ignition module in the HEI. They tend to show those symptoms when going bad, but only act that way after being run awhile and heating up.

It is most likely collapsing vacuum line to the vacuum advance. Chevy 454 are notorious for this and my 1989 454 did it. I have had all the lines replaced as that is the only cure if it is the problem. There are about 12 feet of vacuum line. The plus to doing this first is it's cheap to do.

BTW what is the engine in?

check fuel pressure and volume in output. Next spark controller, etc, HEI or coil which every you have. Ark or distributor cap carbon tracking or cracked.