I have a 1946 flathead ford, new head gasket, pertronix converted distributor, eddy Meyer intake with 2 stromberg (back carb has a 1" aluminum riser with vacuum), electric fuel pump. Car start and run fine on open road (180degrees), as soon as I hit city or traffic temp goes up to 190/195, after few miles it start running rough until it dies on my, usualy when I stop to a light or stopped in traffic. Gas arrive to the carbs and there is sparks but cant restart. After cooling down for 30 minutes it start again and goes until I get stuck in traffic and dies again. I'm thinking of some sort of vapor lock, any advice on what do to and check??