I drove to the Nationals today, about an 80 mile trip in rather hot weather. The car went very well, engine temp and oil pressure remained stable throughout. However, about an hour into the journey the car started stalling when we came to a stop, because it was trying to tickover at about 400rpm. Prior to this journey it tickover was a nice stable 600 to 700rpm. Once we got to the show I screwed in the throttle stop until tickover speed was restored to 600 to 700rpm and it was fine for the journey home. The thing I don't understand is why did the tickover drop? It took a good couple of turns of the screw to get it back to normal. I did wonder if the distributor might have moved, but it felt tight.