For one thing, get rid of the 225 MGs on your elevator halves. I realize that you'll have to open up the plane again to replace them with a larger servo, but, is it worth loosing the plane?
I've run the 225s for years on pylon racers without any problems. I've lost a few in 40-size Fun-Flys, due to 205 & 225 failures. Anybody that thinks that a Fun-Fly servo doesn't see the stress and strain that a pylon racer exerts and more, isn't flying that aircraft the way it was designed to . The 225's gear train is too small for this application. Metal gears makes it even worse in the case. The vibration of the big motors has a tendency to wear the metal gears a heck of allot quicker, thereby creating slop. If you don't have slop in the drive train now, you will soon! And you think your flutter is bad now! Its going to get worse! You need the larger gear train, and nylon gears to absorb shock. I realize that this is a controversy regarding metal vs. nylon, but that's life.
Take my advice, and replace those 225 MGs.
Once again, My 2 cents.
Kevin