Truck running rough at idle, dying when hot.

[Jobe72]

I have 1972 GMC with the stock 350/350 combo. Nothing has been done to the engine that I know of. I am running an Edelbrock carb and converted the engine to HEI. Been running great for the last year that I have owned it and I love droving it. In the last week or so it's been getting warmer down here in Texas. Today while on a road trip when I would come to a stop the truck would idle really rough and want to die unless I gave it a little rev up. Runs great, no problems and I haven't changed anything. Does not do this when cold, starts right back up no problem.

Any thoughts? Ethanol in the gas? Not sure where to start on this one...yes, I've checked all the hoses and everything under the hood.

Thanks