Every holley I've had has alway's had problem's missing and bad gas mileage. I have yet to see one function correctly. I am a ford liker but I hate to admit that there carb's are junk from my experience. I seen a 318 mopar run holley carb, missed and spuddered, even with a rebuild kit in it, then replaced it with a rochester carb and not a lick of problem with it. Motor ran better, better gas mileage, and less wear and tear on the starter. The only thing I can think of is the neoprin float's in a holley could be screwing things up, does holley run brass floats, maybe that might cure most of the problem. I am not sure since I am not too familar with carbs.