Constant misfire ??????

[Charles Levien]

My Chummy used to get hot and bothered and misfire after about five miles (when I mentioned this, one of the other club members said it reminded him of his wife).  Turned out to be an air leak into the manifold - so it was running lean.  It proved very hard to spot.

I’ve had some experience with manifold problems ( no pun intended) climbing up the Gross Glockner pass in our Opal. A tell tale is loss of power, running hot and plugs burning white ( ish). Not much to do with misfire. 
I remember trying to find a misfire a few years ago — it turned out to be a fractured connection in the distributor — that also got worse as the engine heated up.