I had a 340 once that did that when the plugs "overheated" A new set always fixed her right up.The root cause of that was too-lean running.
My 367 does that all the time......... if I forget to reset the rev-limiter,lol.
Back when I was racing, if I left plugs in over the winter, no matter how old they were, it would have a high rpm miss in the spring. New plugs cred it.
