Looking at the plugs I have a nice tan colour on the electrodes, which is good, but the "threaded part" of the plugs are covered in dry black carbon? Is this something to be concerned about? Do others see the carbon on their plug threaded section or is it reasonably clean? I don't think it's running rich as the electrodes look good. I have heard that TR3s tend to load the plugs with carbon when idling but it just burns off when driving? I believe the choke is returning properly. Would I be further ahead to try a hotter plug or leave things as they are?