One of my friends had this same problem with his UCD60... Try unplugging your servos from the receiver one at a time and twisting the extentions up as much as you can without making them too short. I run HiTec digitals in my models and they come with the servo lead twisted already, make all your extensions look like that too and it should fix your problems. Twising the wires breaks up the signal radiating out of the side of the wire but does not affect the signal going through the wire, hence making for less channel to channel interference inside your airframe because servo leads are running next to each other lenghthwise down the fuse. Also, I dont know the capabilities of your radio but if you have an extra channel and the ability, run your elevators on two separate channels mixed together and throw out the reversing Y if possible. The reversing Y has to be re-centered frequently, especially with temp changes. Let us know what you figure out!

Brian