I spent all day at the boat, the trim tabs have nothing to do with my problem, only that when they are up the engine rpms go up from 4500 to 4800 which is where I have my problem. Only on port engine, starboardengine water pressure is normal. Engine temperature stays perfect at 154 degrees. I payed close attention on a test drive to the water pressure based on all your great feedback and the engine water pressure is fine up to 3500 rpms, it's over 8.2 at 3500. Then as the rpms increase the water pressure goes down to 6.5 at 4500 and then falls to the low of around 6.2 when I go WOT, 4800 rpm and alarm and guardian mode shuts that engine down but it does stay on, I just go back to idle to stop the alarm. So I replaced the water pressure sensor and it didn't make a difference. THEN I saw that the connection from that engine to the water heater(which doesn't work) had a huge leak in the connection, the connection on the water heater corroded off. So I took the hose and bypassed the water heater by taking the hose that came out of the engine to the water heater and looped it back to where it goes back into the engine. I was sure that was the fix so I went out for a test drive and there was no change! I was so disappointed. I replaced the water intake pump 6 months ago with a stainless steel hardin pump so i know the impeller is good. Also had new intake hoses installed when I bought the boat two years ago so they are good. Also, checked basket on the intake line and it was clean. I don't have any way of getting the code unfortunately. Have a survey on Monday so looking for a hail mary that I can fix it before that. Any other ideas? Thank you so much