You should take it to a certified tech to get any codes pulled and looked at. Seems to be acting erratic.
If the engine raced with the throttle closed, then unregulated fuel leaked into the motor. It could be from a leaking lift pump diaphragm, a flooding VST, or an external gas leak that allowed fumes to be ingested into the motor.
Take it to the dealer right away for inspection, do not use it until fixed. Evinrude is pretty generous on participating in a normally covered repair if warranty has recently expired. Your dealer can contact Evinrude and plead you case.
"There is never just one thing wrong with a boat";
-- Travis McGee, main character in a book series by John D. McDonald
The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with electrical or ignition systems.
The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.