Why are my spark plugs are fouling?

edward, when you say they are fouling up, it is important to look at the plugs itself and make some determination based on the findings. I attached an image and causes of plug failure. You should see which one comes close to your plugs and take it from there. If it is the same plugs over and over, I would think that you have some failure on those particular cylinders. This could be from bad valves, to bad rings, to a cracked head, to a bad ignition module..... hope this helps to get you started.