HELP!! Pitching problem
 

I have a new hobbylobby revo that pitches up baddly during a high speed turn.If i pull the collective way back it flys ok.I had 2 other revos and they did not do this...i could fly them almost full power/collective and would maintain good level flight throughout the turn.This new revo almost does a loop by itself during a turn with alot of collective...any ideas....All helis have the same blade angles...-7 and +7......thanks