I am working on a yamaha moto 4 with the oil cooled 350, I first couldn't get it to start, then I relplaced the battery, spark plug, starter relay, and cleaned out the carb. Now it will start and idle normally at half choke, if I turn the choke off it will die even when warmed up. When I drive it, I have the feather the throttle a little until I feel the power come on and then I can drive normally but it will lose power randomly and I need to feather it again or it will die on me. I am trying to figure out the cause of this, I double checked the main jet and it is clean. It ran perfect up until I blew out the rear tires and then it sat for about 3 years and now it is having these issues, I have been searching around and noticed some people talking about muffler clogging, is there any chance that this could be a part of this? Im not sure if a mouse climbed in there and clogged it up over the years or what. It is also back firing a little bit, much less after I double cleaned the main jet out. It seems like it is back firing through the carb and not the muffler. Also, would I just be better off replacing the whole carb with a new one? Any and all help is appreciated