Hy Chenzo, have you checked the torque on the intake/exhaust manifold bolts, and the carb mounting bolts?
I'll check the torque on the intake/exhaust manifold bolts. I'd be surprised if that were it though. If there is an intake manifold leak, the problem would be worse at idle (when manifold vacuum is highest), not when the throttle is open. The engine idles very nice. It's when I hold the throttle open that the stalls and backfires occur.
