Mercury Outboard shaking and not going past 3000 RPM

From one day to the next my Mercury Outboard would no longer get past 3000 RPM. It seemed to run fine up to 3000 RPM but once I got at that RPM the motor started shaking heavily and eventually I got 6 beeps.

A lot of people with similar problem but very few forums provided an answer. One forum eluded to the Neutral Safety switch. Not the one in the remote controller but in the motor itself.