Club Car fe350 with 290 carb

[sontours]

I am working on a 97 Club Car transporter. It starts up fine and idles. Key start model. Occasionally I can get it to accelerate but it usually just stays idle Inc then when I let off the throttle it sort of revs for a moment. I am trying this at the carb so linkage is all good and governed is not part of it. What I found today was that if I cover intake throat with my fingers I can then get it to rev like it should. Suggests to me lack of fuel or too much air. This carb is brand new and is the third new one I have tried so I assume it is the motor. Spark is good etc.
any common other things to check?
As I mentioned it is a 350 but the carbs we had here are for the 290. Anybody ever tried a 290 carb on the 350? Could that be the issue? Seems like it would still run ok just not get enough fuel to run faster with a smaller carb.

Thanks in advance.

Phil