I tried the S area mode with AF-C and got more keepers. Thank you all for this tip. It was a very good suggestion. I read on another forum about the a3 setting, they recommended changing it to 1 and then to Off and see if it makes a difference. Sound advice?
By the way, I tried the new 24-120, boy, I miss my 17-55! The zoom ring is quite far from the body and my hands are not big enough for a comfortable reach. And the way the barrel extends when you zoom in... Well, now I have a better body and an inferior zoom. This is my price for moving to FX (just kidding).