Servo twitching
 

On my HPI savage i just finished building my throttle servo has a twitching problem. When I push the throttle about half way the servo twitches for a little while and then stabilizes. I am concerned about this because it may affect the intake of air to the engine. What is funny though is when I reverse the servo on the transmitter (Futaba T2PH) the servo does not twitch, but then I have to hold reverse to go forwards. The same thing happens in my TT01 but with the steering servo, and in each case the twitching only happens in one direction. I am pretty sure that it isn't the servo, might it be the receiver? Both of my AM band r122je receivers are over three years old and have been used a lot. Would buying a new receiver fix the twitching problem?