That sounds lean to me (unless it's SO rich in which case you'd see black smoke when you step on it). If you just ease into the throttle and it still stumbles, probably not squirters.

What jets are in the carb? Fuel level in the bowls set? Fuel pressure?

Does it run OK once up to speed? Or is the stumble always there?

Edit: Didn't someone once say that 90% of carb problems are in the ignition?