Yamaha ox66 issues

[striper56]

I have a 2001 Yamaha 250 hp ox66. When I run the motor between 2000 and 2400n rpm the motor will lose rpms and sometimes almost come to a complete stop. This happens while increase or decreasing the rpms. The motor runs great from idle to 2000 rpm and above 2400 rpm to WOT.
So far I have done the following

replaced all fuel filter
replace fuel line from tank to the motor
replaced vsp filter
cleaned o2 sensor
replaced plugs
bypassed the flow scan

Any help would be appreciated.

Thanks