I currently own and drive a HPI MT2. It runs fine but I engage full throttle with the engine off and when I put it in neutral the carb opening is about 1/4 throttle. When I put on the brake the carb moves back to about 1mm. Also sometimes I am driving the car around and at neutral the car doesn't move at neutral and after a while it starts moving in neutral like the idle speed is to high. Could this have anything to do with it?

Thanks in advance.

sounds like your throttle linkage, unhook the servo horn, or the piece that attahcs to the servo, set the servo to neautral by using your radio. then making sure the carb is closed set it back on so when in neutral the carb is closed

Yeap, thats a linkage problem. A throttle return spring will help also.

yep, use an old exhaust spring to help pull carb back to its close point (1mm open or what ever the setting may be). Also, check out how the rustler linkage is set up, Im running that set up on my rush, it has the spring on the rod between the servo and linkage, set the tention so it helps push cab back to closed setting. Under 10 dollar fix.

i think all traxxas has that, but my bros duratrax has it too