Bog/Stall when full throttle
 

Hi!
For starters I have a Can-Am Renegade 800 -08 :)
The bad part is its giving me a headache cause when i give it full throttle it starts to bog / stall for me.
I can start it when engine is cold and drive it at 2000 rpm without problem but when i start getting at 4000-5000 rpm it just starts behaving like it don´t get enough fuel or way to much fuel and bog/stalls.
If i release the gas throttle i sometimes can get it to run before it dies completely. If it dies on me i have a hard time to get it running again.
I can crank it over and over but it don´t start.
Found out that it i push both override and start button and give it a little gas i get it running but it runs really really bad. And then after a few minuts on 2000 RPM it starts running normally again.

I have absolutely no idéa on what might be wrong :(

I have been running it in water/mud a few weeks before this trouble started, but when the problem happened i was running it on the road, then it just died and i had to toe it back to my house, couldnt get it running at all.
So i changed gearbox oil, engine oil, coolant fluid, break fluid, fuel filter, air filter and spark plug, removed the battery for a week and charged it.
I got it running atleast, BUT the error on full gas throttle was there.
I then changed the fuel pump today but still same error.

I checked the P Codes by pushing it to EH with the mode button and holding mode button at the same time as changing headlight switch from full to half three times in less than 3 seconds but it just say "no active p codes"

Anyone have a clue what the problem might be?

Im really happy for every help i can get
RGDS André

Others--> I did last night notice that oil came out from the rear top valve cover, well between cover and gasket. I´m replacing the gasket tonight. Is it suppose to leak oil from there? Could this result in compression loss?