I have an LA 360, weiand stealth intake, with a carter 625cfm AFB. It runs great beyond 1500 RPM. It stumbles, and misses a little when leaving a light, until the RPM come up. Timing is at 14 initial, and 34 total. Any help would be appreciated.
1500 RPM is where the primary booster begins to flow so we can narrow it down to the transfer circuit. Disconnect the pump shot lever and drive the car on just the transfer slot easing into the throttle as you do. The car should not have any drivability issues and if it does then you have a problem there and it needs to be further investigated. Never use the pump shot to cover transfer slot issues.