The wire harness is usually not repairable, it has to be replaced. You can check the condition of the wire insulation by striping back the black fabric wire wrap on the wires that attach to the temperature sensors located on the top and or side of the thermostat housing. Sometimes you can also tell by looking carefully at the wire where it enters the temperature sensor connector plug(s). You can also check the wire harness part number tag although it is a bit difficult to find. It is usually located on the wire harness where it runs across the bottom drivers side of the battery area. If you can find it, Phil at FASTLANE PARTS (sponser of this web board) can tell you if it is made with the new non biodegradeable insulation. If so, you should not have any more problems. Some of these harnesses (and also ac evaporators) were replaced by the dealer under warranty, This warranty replacement seems to have been more common in cars that began life in the Southern States, probaly because the warmer climate caused earlier failures. A friendly and helpful dealer service department can look up the VIN number to see if this has been done. There is really no way to tell by looking if the throttle actuator has been replaced. Only proof would be maintenance receipts or partial disassembly.