on the throttle to carb arm .....long bar with 2 alen key collars & spring in between .....is if the spring is compressing when you put on the brakes and in turn moving the brake link

adjust the collars out if its not compressing (allowing the brake arm to move) also check for binding of the servo arms

check the throttle trim on your controller as well

hope ya get it tuned and set right & good luck just finished fixing my kids tune up with him as well as one i got at a pawn shop we luv our rc10's

if thats not the cause give me a holler ill look at mine and my kids than try to explain in better detail steps to check across the whole car