I think my engine got ****ed up [&:]

when i press full throttle the engine seems that cant run faster but its going really slow and the sound its not really good. Its not the tunning i was tunning it all the day and still hear this sound that seems like the engine cant breath. I have clear and oiled the air filter but still hear the same sound.

I would like to see some suggestions to what to do or if i need a new engine [][]

I have a mantis with 1st spec axial engine.