Holley 390 stumble

The 390 on he slant has a nasty mid range stumble that I can't track down. When your accelerating it goes from 1st to 2nd fine (A-745 3 speed and 3.55 gears at the moment) but at the top of 2nd it will start to "cough" and stumble all over it self. It also does it when you floor it. I have been playing with different secondary springs, power valves and accelerator cams and the float level is right below the sight plug.
Have I just not found the right combo of secondary spring an accelerator cam yet? I am trying to track down the local carb guy so I can trade the POS Holley for a 500cfm Eddy that has been turned in to a 400cfm. I hate Holleys on daily driers! :angry7: