To quote my previous post (#51) about the idle, you have to make sure you have the idle screw set such that it dictates the idle and not the throttle servo (otherwise you might have stalling issues when you put on the brakes). While the vehicle is idling, if you put the brakes on, the engine RPM should remain constant. Also, there should be a point at which adjusting the throttle trim on the transmitter no longer lowers the idle because the carb's idle screw is now holding the carb open. Factors such as break-in, fuel, glow plug, temperature, etc. may require that the idle be set occasionally.