Thanks everyone for the spark plug cleaning recommendations.  I tried brake cleaner and oven cleaner.  The oven cleaner appeared to work much better.  I had been running the fine wire RE7A L and RE9B T plugs that came with my Renesis.  After cleaning they still had s slight miss at full throttle.  I cleaned an old set of plugs that came with a 1987 engine BUR7EQ L and BUR9EQ T and tried them.   The engine ran better and had no miss at full throttle.   I believe these are the same plugs Tracy has been running in his Renesis.  All the plugs are manufactured by NGK.

Dennis H.