Intermittent problem with 25 hp 4 stroke

[Dennis James]

I have researched this out the wazoo and have found this identical problem in old posts on this forum. I have never seen where it was resolved. The issue is that my 2011 Mercury 25 hp 4 stroke will suddenly lose power, sound the chime and warning light after a short (maybe 200 yard) trip down the lake immediately after launching. If you wait a few minutes it will start and run normally all day! This has happened repeatedly for the last month or so. Once(this last time) it did it three times, but then was fine. I could continue running from place to place to fish, low speed, top speed, trolling, whatever. I have discussed with a friend who is a Mercury dealer and he first thought it was overfilled with oil. I have changed oil and am keeping it at about 2/3 on the dip stick. He says too full is as bad as too low. I understand that the three conditions for the continuous light and alarm is over rev, over temp, or low oil pressure. I have seen the recommendations to unplug the temp sensor and or the oil pressure sensor to see which one stops the alarm. The problem is identifying and figuring out how to do that. I found the MAT which is apparently the temp sensor but unplugging it doesn't seem straightforward. I don't have a service manual. There are three relays on the front of the engine, 1 of which seem to be the starter solenoid. But again without knowing what I am doing I hate to start dismantling stuff. I understand that the thermostat could be bad, but I can't find that either! However the engine is putting a good stream of water out the pee hole and I can feel it getting warmer then cooler as the thermostat works. But maybe sticking first thing in the morning? Anyway since I have seen this exact scenario described several times online about 25 and 30 hp Mercurys over the last ten years or more it is amazing to me that someone hasn't figured it out. Can anyone help