sometimes
Yes, fouled spark plugs can cause engine shaking, and loss or power. I'm not sure about knocking but I'd guess that too.
Engine knocking can be caused by numerous things. Having the incorrect spark plugs, carbon deposits on the cylinder walls, and being low on engine oil may all cause a knocking sound.
yes
Wear. Fouled. Cracked.
A spark plug incapable of producing sufficient spark to ignite the air/fuel mixture.
Fouling spark plugs can happen when the tip temperature is insufficient to burn off carbon, fuel, oil or other deposits and causes spark to leach to metal shell...no spark across plug gap will cause a misfire. Wet-fouled spark plugs must be changed as they won't fire. Dry-fouled spark plugs can sometimes be successfully cleaned by bringing the engine up to the operating temp.
Sound like a fouled spark plug.
if the gap is too large it can make a weak or no spark condition witch can create a misfire. on the other hand if the gap is too small it can reduce the heat of the spark significantly witch can also create a misfire. both conditions may also result in fuel fouled spark plugs.
Yes
Fouled spark plug(s).
if the spark plugs are black because your car is running too rich. your plugs are fouled.
It is either a fouled spark plug or a timing issue.