Engine needs a rebuild?

Brian Bearor said
Tried the treatment. After running 20 miles it fowled the plugs. Pulled them and they were covered with chunks little of oil and oil. Replacing the plugs. Definitely loosened something up. Should I just run or try another treatment?

Sounds like a lot of carbon buildup. I would run it for a bit and recheck the new plugs.

...but 20 miles is the tip of the iceberg with the driving you need to do.