Yamaha F225 surging, Low rpm

[Bull GT]

Hi guys I have a problem that I have not been able to solve for a while now:

I have twin 2006 F225's with 1800 hours. One engine is fine the other will run fine to 3800, you can baby it up to 4000-4100 but anymore else and it will drop to 3200 or so and surge back and forth. We have replaced EVERY filter. We have tried pumping the bulb while running around the 4100 rpm cutoff and no difference. No codes are showing up on the yamaha software.

There was no apparent loss of fuel pressure on the YDS while it as surging

We then had injectors cleaned out, had the VST cleaned, plugs replaced and swapped fuel lines and low pressure pumps with those on the working engine. Working engine still runs fine while the one with the problem now will run fine to 2600 rpm and at full will only do 3100 rpm, whereas the other engine is fine and will spin to about 4700 at wot.

I plan on checking the ignition and injectors, is there anything else that can be done? Any instructions or tips will be most useful. I know another guy had the same problem what was the solution?

We have spent almost 3 full days trying to sort out this problem with no success.

Thanks in advance.

Thanks in advance

[rodbolt17]

3 days on a simple problem?
YDS does NOT monitor fuel pressure on that engine.
thats the first thing to monitor with those symptoms.
did you get the flow chart printout back with the injectors?
if no codes are displayed the ECU thinks all is well.
however it cant monitor in range failures, only the tech lokig at the data can.
your describing a classic loss of fuel pressure or a fouled plug.