BIGS CARBS, anyone use one???

[429mustang]

The carb's actually for my astrovan, the motor's a 355 small block with ported/polished/milled w/perf valve job stock castings (edelbrock performer springs/aluminum 1.5 roller rockers), performer RPM cam/intake (port matched) perf. 600 carb, headers, pete jackson gear drive, built 700R4 trans (2200-2400 stall lockup converter). I know it's a chevy, but I wanted to get it all built and out of the way before I started on my 86 Mustang Big Block project, plus my family's owned the van since it was new so I don't want to get rid of it. Anyway, the 600 carb on it studders sometimes from off-idle, usually from around 10-20 mph, then takes off ok. Last night, I had it running in a parking lot for a few minutes while I changed wiperblades, it started dropping rpms after a couple of minutes then shut off. It started ok, but it seemed like it was flooding out at idle, but I just adjusted the idle mixture and even brought the screws in a bunch from where I started out. I try and mess with it today, but I'm definitely looking for something better/easier to mess with like a Demon or Holley.