Crusader 454 XLI Warning Lights, Quick Loss in RPM

I've got a 1998 Tiara 35' Open with Crusader 454 XLI about 1100 hours. At cruising speed 3200 RPM's I get an intermittent situation on the Port Engine where the warning lights turn on (Oil Pressure, Water Temp, and Trans Temp), an audible warning beeps 4-6 times, the engine RPM's reduce from 3200 to 3000. This situation lasts for 2-3 second then the warning lights will stop, audible warnings stop, RPM's return to 3200, and everything returns to normal. When the situation occurs engine temp is at 180 (normal), voltage meter reads normal, engine oil pressure reads normal and the gauges do not fluctuate during the occurrence.

This situation only occurs at cruising speed after the engines have been running 1+ hour. I made several long runs in the past week, burned multiple tanks of fuel (3+ continuous hours at cruising speed and the situation 2-3 times during each run didn't matter rough or calm seas). Working with my mechanic we've checked all wires to the engine, ground connections (it was suspected we were losing a ground connection), checked the alternator (output is fine), batteries checked out fine.

Any thoughts on where to look next would be appreciated.

I'd suspect you have a thermal intermittent somewhere in the wiring on that engine.....I'd be inclined to get a 'scan tool' and monitor all the ECU inputs until the issue occurs...hopefully, the problem will recur and the source can be located.....without the scan tool, the only other option would be a hit or miss wiggle test.....

Thank you very much for your insight and suggestion. I'll post an update as soon as I have more information.