OK my nova fires up and idles no problem but after about 20 or 30 minutes of driving when I come to a stop the motor just shuts off. No warning no spitting or sputtering just dies. And then I have to wait about 20 minutes before she will start again. I have a holly 4 barrel 600cfm carb . 350 v8 bored 30 over and a hei distributor. Not sure what it is need help with this please and thanks in advance.