I have a 2000 Johnson 90 with the optical ignition system. Its on a 25' Crest pontoon.. I have been having issues with it surging or cutting out so to speak... I have cleaned and checked the fuel filter... Tried pumping the bulb when it did this with no difference... It has done it low and high rpms... Also with 4 people on the boat the other day it was only turning 4200 rpms wide open... Anything else I can try to pinpoint maybe ignition