It is very possable the distributor is defective, what is the part number of the distributor?
Once above BASE rpm, you should be seeing a progressive increase in the spark advance (or spark lead) as rpm increase.
If not, something is wrong.
I can't read the tach while using the timing light, but at a certain rpm the timing jumps from base to full advance - there's nothing in-between.
Have a 2005 55hp Merury Seapro. Engine starts normally and idles normally but loses power when sailing for maybe two or three
That it would.Good luck,hope it all works for you