I have a 1973 440 chysler engine.it starts right up idles great, when in neutral if wind it up it goes up well backfires thru carb near top end. when u take it out under a load it runs smooth no misses, while under load and above 2300 rpm the engine just wants to die and again back fires thru carb . I have checked the following. no water in fuel, new fuel filters, new fuel pump. the ignitions are Mallory electronic and new eldelbroc carbs. Thanks