Does it start right back up? Does it do it only when the blades are on? Could be a bad safety switch or a wire is pinched and shorting out. Any repairs just made?
It just dieing, and especially with blades on, doesn't sound like a fuel\carb issue. It could be a deck issue such as a idler pulley locking up. After it dies, carefully feel each of the idlers. One or more may be hot. This would indicate bad idler bearings. Same could be true for the spindle bearings. Fuel starvation usually causes the engine to stumble before dieing.
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