misfire when cold?

[chedder]

when the engine is cold for the 1st 1/2 mile or so, I have a misfire @ 2500 rpm (feels like a rev limiter cutting in) and a brief hesitation when depressing the throttle from tick-over.
When the engine temp gauge starts moving the misfire clears completely.
Plugs dizzy cap and leads are ok, new ignition amp fitted. any ideas?
Also what is the best timing set up for the dizzy on a 350 fitted with a vacuum advance dizzy?

[dickymint]

Just a thought - Many Wedgers advocate removing the cold start injector plug. Maybe you have done this? From my experience 350's run ok with it fitted (and working) to do what it says on the can! ie. helps cold starting:spim:
as I say just a thought.