2004 vz250 hpdi missing when throttle back to 3000rpm

[Thehunter]

I have a 2004 250 HP hpdi Yamaha outboard that keeps missing when you accelerate past 3000 RPM runs fine but when you bring it back to 3000 RPMs it immediately drops to 2000 and starts missing sometimes if you slowly accelerate it doesn't make it to 3000 RPMs before it starts missing and will not accelerate past 2000 RPMs the problem has been intermittent and is going on for 3 years. It seems to mess up more when under load when I take it to the Yamaha technicians it never fails of course any ideas would be great and I was wondering what changes on that motor when it hits 3000 RPMs because after 3000 RPMs it runs perfect