Zephyr Cove is on FIRE!
Check compression, should be around 125-130 in each hole. Keep the plugs sprayed with CorrosionX along with everything else under the cowling. The bottom plug always gets rusty first if you don’t. Not sure why you have that buildup but compression test and new plugs. Don’t cheap out, buy the NGK that are specified for your motor, they aren’t expensive.