Yes, bladecx, I do know what may be wrong:

Your blades are out of track.

Here is how to fix them: put some different colored tape on each blade tip so you can tell which one is higher.
It is best to do the tracking with the heli on the ground, it is way too easy to crash while trying to see which blade is higher.
Hold it down somehow, securely, and run it up to about 1/3 to 1/2 throttle in normal mode. Figure out which blade is higher. (Actually the tracking should be done at zero pitch, but this is good enough for a first pass.)
Before you try anything else, switch the blades, and check again. If it got worse, put the blades back. If it got better, good.
Now you need to decide if you want to lower the high blade or raise the lower blade. If you raise the lower blade you will have slightly less head speed at hover, and vice versa.

To adjust the tracking, unhook the pitch control link of whichever blade you want to adjust, and screw it in or out by one full turn and check again. Repeat until blades are in track as best as you can get them. If you lengthen the link it will raise the blade and vice versa. Check after each full turn on the link. Don't worry if you can't get it exact. If you make a change and it gets worse, undo the last change and move to the other blade.
Keep track of what you are doing, which blade, which grip, raise, lower, etc. because it is easy to get confused.

I mark the blades and the grips so I can tell them apart always.

This must be done whenever you change blades or any part of the head that may affect pitch--like any part of the head.