I have a '98 Bayliner Ciera 2855 - 7.4 MPI that's been running great until this week. After running 15 minutes at 3600 RPM, she started to slowly decelerate. (I thought it was throttle creap.) RPMs continued to fall to 2500 then oscillated wildly. Utlimately fell to 1500, then she quit. My...