I'm looking for some carburetor tuning assistance. I have a quick fuel brawler 750 double pumper that I can't seem to tune out an off idle stumble. This carb is on a 460 in a 77 f150 4wd manual trans truck. Engine setup is a 72 block zero deck kb flat top bottom end. Heads are stock 429 PI. Intake is a stealth. Cam is a solid lift from the mad porter. 237/[email protected], 600 lift. L and L fender well headers with 3" glass packs. Distributor is a duraspark with 6A box 20 initial 36 total with 12 degree vacuum can. The engine runs great except for an annoying off idle stumble that happens at low rpm. For example I can pull off in 2nd, accelerate to about 1800 rpm,shift to 3rd rpm drops to about 1200, start easing down on the gas and the engine stumbles then pulls on fine. I'm fairly sure it's a lean stumble. I have and old edelbrock narrow band in the cab and it goes full lean during the stumble and the vacuum gauge drops down to about 5 or 6 inches. I have been able to improve it some with a larger shooter 0.039, orange accel pump cam, and a 9.5 power valve. But the stumble is still there. Better on warm days. Worse on cooler days. Worse until the engine is fully warmed up. Does anyone have experience with these carbs? I need some advice on what I should try next. If I accelerate harder the stumble doesn't show up. It's only when I'm easing around town or trying to save gas. So it's at low rpm with a decent size cam and big intake. I like the cam. Would a different intake help?