Found the problem guys. All this time it was the damn spark plug. I had a Champion L86C plug but I think I ruined it when I was running a little lean for 2 weeks. Also, with this spark plug, I noticed that it runs best in cold weather and worse in hot weather. So, should I get the same plug or a hotter one? If I run a K&N or no filter, I would need a hotter one right and wich Champion plug would be right?