60 hp merc 3 clyd looses power

[merc_MAINE]

hello I have a 60 hp merc 3 cyld 2 stroke ser# 6549539 wich best I can tell is a 1984 has run perfect for 4 yrs I owned it had to put set plugs in every yr cause i idle/troll mostly fishing. Was tubing for a change with it ran pefect and out of the blue was like someone had pulled back to 3/4 throttle no skip nothing just reduced power, once at dock it did sputter at idle pulled plugs and found #3 & alittle on #2 fouled started checking and found a wire one from trigger box to #3 cyld coil corrode and when i touched it broke so ran new wire from trig box to # 3 coil put new set of plugs in went out ran perfect for 15 minn then same thing no warning at all just like throttle pulled back to 3/4... and intermitanly would try to catch a cyld (fire) then nothing after a few attempts to catch the cyld....checked wires again and found another wire its the very top left wire if you are facing switch box goes up to under flywheel (stator wire?) repaired it put in new plugs in 3 & 2 but this time did noty correct problem runs worse wont stay ideling unless i turn up throttle but once engage motor stalls... took a plug tester and found #3 cyld had the brightest flashing light on the tester all wires good that i can see my dad has a 70 merc and we found a bad switch box on his when it got wet wouldnt start napa had 32 of them in stock so tells me issues with them.. pulled fuel filter and strainer clean its deffinatly a firring issue cause it did try to pick up cyld(s) loosing fire a few times....
ANY IDEAS?