Hey wnuk, how do you have the antenna routed? I put mine right out of the 4-1 to the skids and then back and forth until I have about 12-14 inches left and then run it trough a plastic tube strapped by pieces of rubber bands to the skids. I had MAJOR glitches before I did this and after none. As you said it was like it went to negative pitch.

I didn't have any pics of my ant route but I drew it in blue as it would be on the opposite side. Blue is the antenna, yellow is the plastic push rod I used. I had a ton of glitches before I did this, now it will suddenly drop on very rare occasions.