I have a 2015 ZForce 600 and it loses power on any incline, on flat surface it seems to run fine, but as soon as I get to a hill, wether on the trail or the road it loses power significantly, I can go from 30mph and it will drop to 8mph, the machine has 2500 miles and it's always been maintained but it's been like this since I bought it new and is getting progressively worse, any suggestions would be greatly appreciated, also is anyone else having this problem.