I just bought a 2000 150 EFI. Boat runs great off trailer, once I’ve run it for about 10 mins I go to idle. Then go wot it only gets to 2000 RPM. If I leave it WOT after 1-3 mins it will come alive and run great. But it does this all day. I have replaced all fuel lines from tank to fuel pump. New mechanical fuel pump, new electric fuel pump. I have a clear inline filter that I set up I am sure it’s getting fuel flow. I had some questionable wiring on trigger so it got replaced too. Tested stator it’s good and is charging while running. Replaced plugs with new proper plus for engine. Had compression check done all passed. It’s at shop now and tech said it looks to be the ECU cutting in and out. But is looking for a ECU to install to test before he’s sure. Sound about right any other suggestions. I am a mechanic my self and have looked over everything wiring all looks good. Just hate to throw $$$$ at it. Oh and it only does it under load.