Not really relevant but I also had a slight misfire recently. I changed the coil and plugs which made no difference but I did notice it only occurred when the engine was hotter than normal especially on a run from Scotland to Norfolk in hot weather and heavy traffic, I could control the engine temperature with an electric fan. I considered fuel vapourisation and rerouted the petrol pipe between the fuel pump and the carbs when I got home so it avoided any hot spots and the problem went away. Result.
Cheers
Richard