I have a xtm .15 in my hpi nitro mt. Well when i start it up it runs good for a cheap motor. After i run it a while it start to get slow and take forever to get up to speed. I tried to play with the carb settings but i dont have the instructions on setting it. It has plenty of blue smoke coming out of the pipe when you open it up. so i dont know. What do you think it could be?