Would you by any chance be flying outdoors, I have noticed with my blade cp and 4 in 1 that as soon as things (4 in 1) cool down (about 5degrees C outside) the power drops and the helecopter begins to wobble and eventually becomes to difficult to fly or hover. If I bring it inside and run it, it recovers in about 20 to 30 seconds back to normal operation.
I know your first thought would be the lipo's cooling down and that the power is dropping off, but this does not seem to be the case as the battery remains warm to the touch. I have much experience flying planes outdoor in the winter using lipo's so I am sure this is not a result of the battery cooling down.
I think it might be something to do with the electronics inside the 4 in 1???