It's highly unlikely that the location of the servos is the problem.

It flew two nice flights that morning with no trouble, this indicates that the basic design or layout is OK. RFI does not suddenly start leaking unless something changes.

You say it loks up just off idle. This points at something loose that is vibrating. Check the ignition ground on the engine, anything else that can come loose. It could also be something has broken loose inside the ignition box.

TF