Well you are running an AM radio system it looks like. Am radio systems always have problems in 1/12 cars in my opinion. I've never seen one work perfect... Maybe it might be time to upgrade? JR Propo has some good deals on a XR3i and they are around 120 bucks for a radio/rx combo without servos. KO propo also has a good intermediate FM system called the presto.
-Korey