Merc 225 Slip into neutral

[mpgast]

My 225 EFI slips into neutral @ 4500 & up when going into 3-5 footers. It rides up a wave and when it hits coming down it slips into neutral. The RPMs do not come down. I have have to throttle down. Put it back in gear and it runs fine until we hit another good wave. Any ideas?
Thanks,

[boats.net]

Varify all cable adjustments and shifting components.