Ok guys a little help is needed here. First some background, I have a 3DHS 85" Katana running a DL50 with hs5955tg servo's. I'm using 2 7.4v lipos through 6v MPI regualtor on seperate switches. I also have a lipo on a 5.4v regulator for the ignition running through a Jomar optical kill with all 3 switches being JR heavy duty. The rx is a spektrum ar9000 with an extra remote rx added, using an xp9303 with module for control. I have around 2 gallons of fuel through the plane and up till just recently no problems. First thing I noticed was flying at a local funfly the rudder kicked on the plane. Landed the plane and nothing could be found. I bought a flight data recorder a couple days later and 4 flights later, nothing happening, data recorder showing good numbers, nothing over 130 fades in a 10-12 minute flight. Thought it must be a fluke, around 6 flights later, the rudder kicked on the ground as I was moving out to the runway. Brought it back in, again nothing out of the ordinary, rolled back out and put it in the air, 5 minutes into the flight the rudder kicked again, so I brought it in. Now I'm showing high numbers on the data log. Changed out the rudder servo with a new servo, passed a range check motor off. The next time I'm at the field, I start the motor and start doing a little tuning cause I changed to synthetic oil. While I was adjusting the motor the rudder starts twitching and the throttle starts surging, in less than 3 minutes the recorder starts showing 346 frames lost, 0 fades on any of the antenna's. Shut the engine off and it's still twitching. OK so I take the plane back home and start going through the system. I changed the regulators, changed the switches, put a brand new JR DSM rx and remote, changed model memory, unhooked the optical kill, Used a different transmitter, used different battery on the rx (6v nimh), changed extensions, still no fix. At this point I called horizon, have spent over an hour with them, they're convinced its electrical. Called DLUSA, and was told it's vibration, not the ignition. Still can't run the engine without it glitching, throttle rudder and aileron. On the advice of a local club member, I changed out the plug and switched to a different brand of extension, was using Hitec HD twisted, now using JR HD and it'll pass a ground check again with engine off, but still can't pass with the engine on especially around low rpm and idle. Called DL again, and was told still don't believe it's an ignition problem, that it's a vibration problem, but I can send the ignition in and he'd check it.

Ok, if he's this convinced it's not the ignition it's got to be something else, I started it up running good everything is great, it's passing a range check for the first time with engine running, but I'm a little unsure of this so I let it run a few minutes, and just when I think I must be in the clear....... It surges and kicks the rudder.[>:], so I start unplugging servo's both ailerons, still kicks, and the frame numbers are climbing. Pull the elevator servo's, the twitching stops. Start plugging them back in 1 at a time, both elevators nothing, then the ailerons, starts surging again, then my engine BACKFIRES, it's never ever backfired before. Sounded like a pistol going off. I shut the engine off and now I'm here posting. I'm at a total loss and don't know where else to go now.

I need HELP!!!!!!!!!!