Bike runs great thru woods, when get into long climbs (1k - 2k vert, at 9k - 11k elevation) it dies. Will start right back up and run for 100yards then dies. If I let it sit longer it will start right up and run for 200 yards. Turn around head down wants to die. Run and die, on and off. After about 5 miles it runs great. Hear there is a sensor near air filter that I can clean? Think of trading in anyway and do not want to unload problem on someone else.