Don't know where to begin. My '71 454 had a complete rebuild, all stock. Entire fuel system replaced including rebuilt Q-Jet. Only mods are Flamethrower distributor and headers. After a few hundred hundred miles of trouble free driving, and only on occasion, when driving at 40mph+ after moderate acceleration, it will stall. Pull over, starts after sitting 5-10 minutes then seems fine. 70 degree ambient. Fuel filter clear. Haven't torn onto carb yet. Fuel pump seems ok. Thoughts?