John Deere LX178 has power loss after blades are engaged. Runs fine if blades are not engaged

Hi,
You are running on only one cylinder. Valve train is the most common cause of that family of engines. You can use a pair of insulated pliers to find which to check. Crank engine, hood open or removed, pull one plug terminal; if engines dies, that is the side it is running on. If it continues to run, that is the side it is not running on.
Ignition is only about 5% the culprit on the water-cooled Kawasaki.
Peace,
Clarke