Motor won’t go full throttle

[Draw]

I have a 2018 20hp Mercury 4 stroke efi manual start. Starting surging a year ago then no tell tale. Replace impeller and flushed all pieces out and tell tale fine. Wasn’t able to fish last year. First time out this year, would not go full throttle, so replaced portable gas tank lines, fuel demand valve and bulb and changed to ethanol free gas. Also replaced fuel filter that seemed clean (only 15 hours on motor). Changed spark plugs. Second time out, same issue, but would stall. Took VST apart, looked clean, but high pressure pump locked up, so replaced yesterday. Checked low pressure fuel pump and no leaks. Put ear muffs on and idled fine for about ten minutes. I will take out this weekend to see if WOT issue resolved. Do you think I have covered all bases? If still has issue not sure what to do next. Thanks so much for your input.