Johnson 25hp overheating

[3horse53]

I just received a 25hp Johnson from my Dad that had been in storage for 4 years. I took it to a mechanic and had the water pump replaced and checked out before it ever went out on the lake. The first time out, ran great until I was in trolling speed for about 2 miles, had a hookup, shifted to idle while landing fish, when engine died. After several attempts to restart noticed that the engine was quite hot. So removed hood and checked motor. You could hardly touch rope assembly. After about 30 minutes was able to restart. It ran good and cool.
My question is at an idleing speed could the problem possibly be the thermostate?
This motor has been used both in the Pacific Ocean and the Sea of Cortez.
Lynn

[boats.net]

Yes check the thermostat may be stuck closed.