I would give Mark a call if you lost this much speed and all you did is change the spark plugs and had the prop worked. You may want to put the old spark plugs back in since that is an easy test to see if it runs any different. I have had this happen to me before. No explanation for it. Rember hotter weather also has an effect on horsepower.


Modified by bruce180vf at 10:44 PM 6/1/2011