I see in one of your previous posts you mentioned the plugs were soaking wet. My question would be, are the tips of the plugs coming out white or dark? Having asked that, if it doesn't run more than a minute, they may not show any color.
If the spark plugs are literally dripping gas when you remove them, then it is getting too much fuel. The symptoms, only revving to half throttle, would indicate the opposite however. We both know it can't be both so we have to determine which it is then run down all the possibilities that could create that scenario.
Dripping in gas would sound like maybe the needle and seat are leaking, or the float arm spring is too light. However, it sounds like you had this problem before and that is exactly why you cleaned the carbs. Just to be sure, did you say cleaning the carbs did not affect the problem at all? Or, did it not have this problem when you took the carbs apart and this showed up after going through the carbs?
If you think the problem is electrical in nature, you can use an automotive style inductive timing light to check the ignition. First, you can put the inductive lead on each plug wire and try to rev the engine. If you loose spark (flash) on any cylinder, then it is definitely electrical. If you don't loose spark, put the #1 cyl @ TDC and make a mark on the coupler. Start the ski back up and try to rev it to see if the ignition wants to advance or not.
Let me know,