1976 OMC 140hp - engine shutdown after running well.

I recently had my '76 140HP OMC stern drive out and everything was running great. It was the first time out in a few years so I wanted to give the engine a good run. Everything was running great but about 45 mins into the run (maintaining between 3000 and 3250 rpm) the engine began to sound like it was "missing." This kept getting worse so I backed off the RPM's to about 2200, and then further down. Unfortunately, the engine stopped and I couldn't restart it. The max engine temp I saw was approx. 170 F. This quickly lowered to around 140F while I was ramping down the RPM's. Once I got the boat home (after a tow back to the dock) I tried starting the engine and it fired right up. Any ideas? My mechanic things the boat got too hot and the pistons expanded. Could there have been to little fuel in the tank? The fuel guage read a little above 1/4 tank.

1976 Marquis Sting Ray, 140 HP OMC Sterndrive. Well maintained.

Ayuh,.... It'll run Bad, 'n be down on power with a Lean condition,....

Fuel in the tank is required,....

Check the fuel Filters for Crud,...

Does the carb need to be adjusted? Engine fired up with no problem once it cooled off. Just put a new fuel filter in it, though it can't hurt to check it again for debris.