Okay, so I did my bro-in-law a favor and picked up a T-Rex XL for him at a deal. Didn't like the links between the servos and the swashplate so I modified the stock plasctic XL frame with some Mini-Titan servo mounts to get direct servo to swash controls, heli flew absolutely awesome (was very happy). Then I wanted to hook him up some more and put a nice fiberglass canopy on ... but wait, the canopy would not fit over the servo mounts, but that's okay as I already purchased and partially assembled a T-Rex S Aluminum frame. So I install all components to the new frame and get it all setup.

Flying it yesterday for him to see (calm wind day, 33 degrees, with snow on the ground) and I started getting this embarassaing glitches with the heli ... it would lose altitude, and sound like the motor was slowing down, tail would shoot in one direction slightly, wth!?!?! I was able to fly it but the glitch would come back once in a while and I would just bring it tail back to me and gain some more altitude. One time it was so bad that I dipped the skids into the snow in the front yard.

What could cause this glitching? It has an Align RCE-BL25G ESC, Align 420LF Motor, Generic 11.1v 2100mah 15c lipo, Futaba 6exhp TX and RX, Telebee gyro, TowerPro SG90 servos all the way around. The rx is mounted in the rear of the frame on the bottom plactic plate, and I have the antenna wrapped around the left skid, and then down through the tube hanging out of the back, the esc is mounted at the front on the bottom plate with the batter on the diagonal tray above the ESC.

Prior to going to the aluminum frame, the electrics setup was the same in the plastic frame and I never saw a glitch. Help please!

Pic attached from flying yesterday (pic was taken by my wife from inside);