Got my motor out of the shop and it ran great for few days. Now it's missing. Under load ( gettng up on plane) it will miss and then run great for a few seconds and then miss again. Once it gets warm, it seems to run pretty good. I pulled the plugs and they were pretty black. Could I be adding too much oil to the fuel and cause this? I'm currently running between 30:1 and 50:1. I cleaned the plugs real well and will try yo run it tomorrow and see if that helps. These motor issues are getting old. I ordered a shop manual online and it will be here soon. But you guys seem to be pretty good mechanics so I thought I would check with you guys as well.