You should see an improvement by using an OS A3 plug. You probably do this first, because it would make troubleshooting easier, such as looking for the o ring leak that Richard mentioned.

As for the wet idle condition, go to the hotter plug and then let the engine idle somewhere around 2600 rpm for about 30 seconds. See how it acts when accelerating. Lean the low speed needle if it gurgles or bogs down. You may need to go thru this a few times, but that engine should put out some good power. Then, set your idle rpms where you.