A weak spark will allow a vehicle to run with an increased octane (ether does that), but it will flood easily too, hence wet plugs. In fact, it might be as simple as burned or fouled plugs.
But I agree that the carb might also be an issue and that it may be an air leak. A quick check is to look down the throttle and see if fuel is squirting in. I am not so certain about an air leak. That tends to show different symptoms.