ORIGINAL: All Day Dan
Dl, you have lots of problems with that installation and not enough detail in the images to see exactly what they are. Follow this advise from Futaba's website. Dan
Guidelines for setting up gasoline engine models.
All ignition equipment, including an electronic kill switch, must be mounted at least 12'', and preferably 14'', away from all radio equipment, including throttle servos, etc. Ignition kill switch should always be on opposite side of fuselage from radio kill switch. All pushrods going to anything related to the engine must be non-conductive (just nonmetal clevises is not sufficient).
If it is a 2.4 system I have to disagree. 2.4GHZ is nearly immune to such interference. If it is a 72MHz system maybe so.
I have been flying RC aircraft for about 70 years. I have NEVER had an interference problem that affected only one servo There has to be something wrong with that servo.
I am currently trying to fly an old Goldberg Ultimate with 26CC gas engine. That engine makes all servos jitter. I had to put in a Hyde soft mount to quiet things down. Maybe thats your answer. It will cost you a bit though