Having a startup issue with port side motor. Happened once last year and a few times this year. Have power to coil but no spark. The first time it happened in just wiggled the wires and it seemed to fix it and basically did the same thing the other times. I was thinking a broken wire but that should give me issues through out the day. Once it fires up for the day she runs fine all day. Every once in a while at an idle I can see/hear it cut out for a split second, maybe drops a instant 100 rpms. I was thinking about just dropping a new pertronix plug and play marine distributor in it. Should I do both sides or just the problem side? Am I wasting my money? Boat is a 88 311 formula.

Check your grounds first. It needs a good ground.

I agree, make sure all connections are tight and corrosion free, even check the battery cables too.

Check the ignition sensor in the bottom of the distributor. The old style sensors have the electrical posts that stick out the back of the distributor. New style has pig tails. If you have the old style replace both distributors with the new syle sensor. Very easy job cost about $80. Per sensor. Part number is 87-892150q02. Sensor assy-ign.

http://www.boatfix.com/merc/bullet/83/83_24.pdf

Print a copy of Page #3 from link above and keep it in the boat, My original sensors made it over 20 years but nothing lasts forever. X2 on the grounds