ORIGINAL: jetfixr
The throttle push rod is a cable actually with a plastic guide. I have a plastic ball link on the carb and a set screw on the throttle end. No, it is not a mini servo. It is full size, but it is just a standard servo. I have everything as far back as I can get it I think. The rx battery is at least 22 inches behind the ignition module, and probably at least a foot behind the throttle servo. I don't believe I can relocate the servo any further back. I will try a new servo tomorrow and see if I get any change. Thanks for the input!
One additional item - many people setup the throttle so that at full "cutoff" trim on the throttle stick, the butterfly in the carb is completely closed. This is important if you want to "kill" the engine using throttle. To do that, the "idle stop screw" on the carb must be removed completely; most engine manufacturers either do that for you, or back the screw out far enough so you can stop the engine with closing the butterfly.
Your servo could be jumping if it's binding on the lower idle setting due to that screw trying to hold the idle actuator open.