Are you using a hump pack or AA batteries? Hump pack will Deff make a difference on how the servos perform but to be honest the stock servos aren't that great. I lasted about a week before I ended up changing them. A lot of people use the steering servo for the for the throttle/brake and buy a new servo for the steering. I upgraded both and it makes a tremendous difference. I do have a fuel filter on mine but if u don't maintain it and let it sit for a while the fuel can gum up and clog it.