60hp Command Thrust

[RPGR90s]

I have a 2019 Command Thrust on a Crest pontoon that starts and idles perfect, but once underway, at higher than idle RPM's. will lose power and stall.
Yesterday, I removed the VST (Vapor Separation Tank) and cleaned out the screen that attaches to the fuel pump. There was quite a bit of debris on it, and I felt that it was the solution.
Re-installed the VST and took it out for a mile spin, at 4,000 rpm. Ran perfect, no issues whatsoever.
Then my daughter and boyfriend took it out and of course it stalled on them. She said they were just cruising at about 1500 rpm.
I had her pump the fuel tank bulb and it started. She then was able to idle back to the dock.
Two years ago the dealer replaced the fuel pump (low pressure unit that attaches to the back of the engine) under warranty.
Any ideas would be greatly appreciated. I'm starting to think this Mercury (made in China) isn't as robust as all the old Merc's from my youth. "(

 

[RPGR90s]

I have a 2019 Command Thrust on a Crest pontoon that starts and idles perfect, but once underway, at higher than idle RPM's. will lose power and stall.
Yesterday, I removed the VST (Vapor Separation Tank) and cleaned out the screen that attaches to the fuel pump. There was quite a bit of debris on it, and I felt that it was the solution.
Re-installed the VST and took it out for a mile spin, at 4,000 rpm. Ran perfect, no issues whatsoever.
Then my daughter and boyfriend took it out and of course it stalled on them. She said they were just cruising at about 1500 rpm.
I had her pump the fuel tank bulb and it started. She then was able to idle back to the dock.
Two years ago the dealer replaced the fuel pump (low pressure unit that attaches to the back of the engine) under warranty.
Any ideas would be greatly appreciated. I'm starting to think this Mercury (made in China) isn't as robust as all the old Merc's from my youth. "(

So, upon further investigation I attached a fuel pressure gauge and went for a drive. The engine starts and idles perfect, delivering 40psi. I drove it about a mile at 4000 rpm and the gauge stayed at a constant 40psi. I then drove the next mile at 4600psi and within about 30 seconds, the engine started stuttering and the pressure dropped to about 19psi and fluctuated between 19 and 25psi. I suspect a high pressure fuel pump failure (I cleaned the screens in the VST already) but was hoping to verify if any other component could be the culprit also.
Thanks!