Holley Carb Issue

I have a Holley 750 double pump carb on my 440 and of lately it has developed an issue that I'm seeking help with. Off idle it isn't as responsive and the problem seems to be in the transition from the idle circuit to accelerator pump. Also, at highway speeds I'm noticing a flutter out the exhaust pipes. I rebuilt the carb 3 years ago and it ran flawless until a few weeks ago. Where should I start in trying to remedy this? Thanks!

Which rebuild kit did you use?

I just rebuild mine with the black gasket kit and had similar problems and what seemed like a vaccuum leak. I replaced the metering block to carb body with a blue gasket and it solved my problems.

I used an AED rebuild kit.

Then my initial thought is float level. The AED kitsch look like they use the higher quality blue gaskets.

The transition is from the idle circuit to the main metering system. Accelerator pump circuit only adds fuel to a quick open throttle with low vacuum.

Understood. Thanks! I was trying to relate to you guys at what point I notice the problem. I will check the float. Also, the fluttering/uneven exhaust flow at highway speeds concerns me.

Drain the fuel out of the bowls into some sort of container, then take the bowls off. If you see brown dust, you have rust in the fuel system which will get by ANY fuel filter made. Most likely came from the underground tanks where you get fuel. Rust plugs up tiny circuits in the carb leading to your current issues. Since you are in cheese land, go by an ag livestock supply store and get some "cow magnets" which are 2-4" long and 1/2-3/4" in diameter. Bust them into pieces like an inch long and get them distributed into your tank in various areas. They will grab a lot of material before it gets to the fuel pick up. For after tank, a trans pan magnet for a Mopar application auto trans from the 90's up works great to slip over an inline fuel filter. It has a hole in the center that you can slip over the fittings. If you are using a canister type unit, find a few rare earth magnets and stick them on the can. Also, save the fuel you drain out of the bowls and let it set awhile to see if any water separates out.

Update: I found a very small amount of fuel leaking from a lower screw on the rear bowl. I tightened that one and snugged the others up and the carb is now perfect again. I'm not totally sure that was my problem or some trash simultaneously worked its way on thru the carb. Either way I'm happy!!! Thanks to all responders!!!!

You had a vacuum leak to power valve
if it happens again when you replace gasket check metering block for straight they warp
PM if you need directions to straighten