RE: Big problem! Interference Galore
OK, so you've got it down to it works without the extensions and not with them.
First, are you sure of this? I ask because by going direct you may have disconnected a pushrod or changed something else besides just eliminating the extension. But if you are certain that the extension is the only variable, then there are a couple possibilities. But I have done what you are doing a dozen different ways without any trouble, so I doubt it's the extensions alone.
One possibility is noise induced by the extension, which is a real longshot. I've really abused the extension thing and never had a problem. Are they good extensions with gold connectors? This is a major source of trouble. Also look at your batteries, are they providing full voltage?
Can you maybe borrow a different receiver? If you are using JR, see about testing it with a Hitec receiver instead. I'll bet the problem goes away.
TF