Then you are still having problems with servo jitter or inteference?

Try a range check making sure that the RX antenna is FULLY extended as shown in the diagrams I uploaded. You should be able to get about 100 feet or so away with the TX antenna down before losing the link. If you still have problems with the RX not working properly at close range, say 10 feet, then you may have either a TX or RX problem and suggest you send BOTH to the manufacturer and explain what you are seeing.

By the way, things to check: Is there any metal-to-metal contact on the throttle linkage? Are you using fully metal control rods from the servos to the rudder/elevator?

If metal-to-metal anywhere, especially at the engine, make that a metal to plastic or some non-conductive sort of linkage. If you are using metal rods from the servo to elevator/rudder, change that out to a metal to wood or use Sullivan Goldenrods or similar for control rearward. Any metal in parallel with the antenna can cause problems. The throttle vibration will definitely cause problems if it is metal to metal.

Check these things and let us know what you have.

Best of luck.

DS.