Help with evinrude 28 spl

[mcbarnhouse]

1988 model number e28eslccr. Motor idled fine for approx 5 minutes. Then Died. Would not start. Finally got it started but only with me fingering the throttle linkage. Took it to the shop and they said my carb needed rebuilding and I had low spark. They rebuilt the carb and changed the charging coil and took the motor cutout switch out of the picture and I still have low spark and the shop is stumped? I am a very inexperienced novice at marine engines. Diagnostic check still says the charging coil? What are the chances that the magnets in the flywheel very weak and that is my problem?