Gap your plug at about .020". It sounds to me like you do not have the plug cap on all the way, you should never need to pull (stretch) the spring in the cap at all to reach the plug. Make sure the plug cap goes on until the spark plugs hex flats are completely inside the cap. They are hard to push on and take off the first few times. If you don't get the cap on all the way you WILL have RFI problems and or dead sticksshortly after take off.