6=8 and bore over?

OK, so is it accurate to say that the engine acts up when you have stopped or stopped moving after the engine is well heated up? If that is the case, then that sounds very much like the fuel heat soak issue that plagues these /6 cars in warm weather and with the new gasolines that are so much more volatile that in the old days. The gas in the fuel line in the engine compartment literally boils inside the line and it does not get proper fuel level into the carb.

There are several ways to cure and treat that problem. They include re-routing the fuel line up from the fuel pump over the valve cover instead of around the front of the engine, insulating the fuel line, a heat shield under the carb, and other such tricks. Also, make sure the exhaust manifold's heat flapper under the intake is closed. And it is discussed in several threads on this sub-forum; search for 'fuel line heat' in the Slant 6 forums. Perhaps others who have licked this problem will speak up.