It sounds like you've covered all the bases. I'm wondering if you don't have a bad receiver. Don't go to PCM however. PCM can mask interference problems until it's too late and they just drop out or go into fail safe. I would try another resistor plug, double check everything, and it that doesn't work try another receiver. You don't have your antenna routed inside near metal or carbon fiber pushrods do you?

Good luck, but whatever you do don't fly it until you get it sorted out.

AV8TOR