Originally Posted by JimN
Start by replacing the one coil pack that.was on cylinders 1&4- if that doesn't fix it, check the Ignition Control Module' ground. I would suspect the IC module befoer the ECM and I ALWAYS suspect bad ground connections before anythibg else.
Someone here replaced their ECM on the recommendation of their dealer and it wasn't the problem- the dealer wouldn't let them return it.
Gone, out doing soft recreational past time with overpowered boat!