Engine Stalled when slowing down from 300 RPMS. Wouldn't Restart

[MuskyHuntr]

Was out on the lake cruising @ about 3400 rpms (25 mph) for about 20 minutes. went to Slow down & the engine stalls out???
Would not restart. Waited a 1/2 hour and still no restart..

Got towed back in to the ramp, drove home Checked a bunch of things... everything seemed OK... Hooked it up to the hose and the engine fired right up and ran fine..

A simialr thing happened earlier in the season.. slowed down from around 3000 rpm's to near idle when I seen sosmething in the water at the last minute and she stalled.. But she started right up and after navigating around the log we were on our way again.

So the question is what makes the engine die like that?
Can I fix it? If I can't then how do I get around it?

Engine is a 3.0 4-cyl Mercruiser 140 HP besides this the engine seems ot run very well.

Any help would be appreciated....Thanks