1981 115hp "evinson"(1/2 johnson 1/2 evinrude) bad idle miss

i have 110 psi compression on all 4 cyl. new plug and plug wires, new power pack ,no dva adapter for further trouble shooting,starts normal sounds great at high rpm starts a "coughing" miss at idle and stops,any ideas?:?:

 

It could be the reed valves.

 

as gonzo says or too lean or both
its a 3 circuit carb so idle air bleeds are looking at you just inside the top of each venturi when you pull the front cover off.
A broken reed will make a miss every stroke (usually) and a lean cylinder will propably do it with a gap of a few seconds..maybe
Badly synced carbs will also do this as will badly fitting throttle butterflys in the carb when the throttle is closed ( as it should be at idle)
Float level too low will also do this
quick test of lean jetted at idle is to just place a pencil into the idle air bleed and that will richen each cylinder, see if problem goes away
It was common in those days to alter the std idle air bleeds to get the engines to purr like a kitten

PS also make sure it is warm enough

 

Is it half n half block?