Have you done much offroad driving on tracks before? Being smooth on the throttle when you apply it helps greatly to control spinnouts. Also slowing down BEFORE the corner while your still on the straight, then keeping on the throttle just a bit through the corner will help you also. And don't cork it until your front tires are going straight.
Softer clutch springs may help tame it down also. You can tune the diffs with different silicone oil if you know what's currently in it.
If it's blubbering oil out the pipe you need to turn the high speed needle clockwise an 1/8 of a turn or less at a time until you reach desired performance and temps.
Sounds to me like you really just need some practice time on the car to get a feel for it on the track you run. No it shouldn't be flipping over moguls, but if the engine isn't tuned to accelerate, and you're not practiced enough to know how to hit them it will not do what it's supposed to do.
Last season there was a double on this one track I was new at. I couldn't hit it right even with a good run at it. I watched another guy nail it starting only from four feet away. He had good throttle control, and knew how to preload his suspension by using it. Me, I was wheelspinning like a banshee aproacing the jump, then spun up it and wasn't able to get the lift I needed to land the opposite jump. Practice time will do amazing things for your setup and driving.
Forgot to ask, what tires are you running, and what's the surface of the track? And does the car got the stock recommended setup on it? The guys here can't really make setup advice if they don't know what you're running. Although I have heard many times the K3 has a standard setup that works basically everywhere. I'm surprised you're having such troubles with it.