As I newbie I would first like to say WOW, I am very impressed with the boats I have seen here, very nice!

I have a Fun Cruiser with a 25cc homelite. I am using an Airtronics CX2P FM radio with 94102 servos (Airtronics). I purchased the boat brand new probably 5 years ago and have only run about one tank of gas through it. The problem I am having is that I only get about 75ft. of range before the throttle goes out of control and jumps wide open. I am using my CX2P radio out of an electronic truck I have to eliminate the distance issue, but I cannot get anywhere near reliable control. I am currently working with 4 brand new AA batteries running the receiver and servos, also the antenna is run down the inside of the hull, towards the bow.

I am looking for any suggestions as to what could be causing my lack of control. Any and all suggestions are much appreciated.