2006 Town and Country engine stumbles and sometimes stalls after fill up.

That was my first thought, that you have water in there that gets stirred up when you put gas in...I don't know what HEET is, if it is alcohol it should work, if not try an alcohol based product specifically made as 'water remover', as it will mix with the water and burn through...OR, you are over filling, topping it off too much and the vapor recovery charcoal gets saturated and takes a few miles to purge. When the pump nozzle clicks off, stop. Don't put any more gas in

OK HEET has methanol, bio-alcohol, same stuff that is added to gas (at least in Calif) up to 10% anyway...try another product. I am not saying there is anything wrong with that stuff, it's just that they call it "gas line anti freeze" and ethanol might work better if there is a LOT of water

There is a emissions system vapor collecting device back at the tank that might be failing or getting raw gas in it. It's supposed to send fumes to the engine to be burned. When you fill up, stop pumping gas when it clicks off. Don't try topping off to the next dollar and see if that makes a difference.