Small Engines (Lawn Mowers, etc.): Craftsman Lawn Mower Idle, briggs stratton engine, craftsman lawn mower

Question
Mower Model 917.388131. Briggs/Stratton Engine Model 126t02-070. I hit a piece of buried tree stump while mowing yard. It stopped the engine abruptly and bent the blade moderately. No other visible damage.  I replaced the Blade.  The engine now starts and runs at about half previous speed.

Answer
sounds like you broke the keyway in the flywheel? That would cause it to be out of timing! And not run properly.The only way of knowing is to take a pully puller and take the flywheel off,there should be a small 3/16/x 3/16 piece of metal that lines up the flywheel with the engine and if it broke or got damaged it is out of time and would run rough if it ran at all! Give that a try,hope it helps,
Jason