The edelbrock gaskets help but it don't fix the problem, I have the same issue same intake and carb setup, you need to block off the heat crossover plate to eliminate the problem all the way, block it off it in the summer then unblock it in the winter. I have two motors same set up the one with the crossover blocked starts like a charm every time in the heat etc then other one with the cross over open gets heatsoak and the carb gets really hot.
