What is your power setup? Things that I am curious about is what voltage and amperage are your batteries? What chemistry are your batteries? What brand are your batteries? Are you running any regulators and if so what brand and model. What type of connectors are used from battery to RX. What switches are used? What brand and model number of servo. What brand and length of servo arm? What is the length of control horn? What engine and prop? All these are contributing factors and usually it's more then one thing creating the issue.