does anybody know the reason why my truck does this?

[blueb8llz]

its not really accelerating, but when accelerating at higher speeds. when i accelerate and stay under 15 mph...no problem but as soon as i wot or even half throttle, then itll start to veer to one side. yes it does this on all types of surfaces. its a emaxx with losi zombie maxx tires.
red shift thats funny how you said about trying one server and disconnecting it from the rx, cus my fren just offered me that advice like 2 hours before you said it. im going to try it out when i get a chance. i ruled out the obvious and the not obvious. i think i pretty much checked everything possible (that i know of) other than the servo issue, but i did check the inside of the servers to make sure theres no broken gears.
so far, it looks like everyone is saying its the servos fault.i really hope you guys are right. any other suggestions just so i have more options to look at?