I've had times where I'm driving down the highway and the internal combustion engine (ICE) shuts off (mostly when going downhill) and conversely, I could be sitting at a stop light and the ICE could be WOT (wide open throttle). Just remember the ICE is mostly disconnected from the wheels, so it's usually delayed in reacting to the electricity needed from the generator. Also while cruising down the highway, the ICE may be at medium throttle, then switch to WOT, then down to a very low throttle. Drive it like a jackrabbit and it will be more spastic in its behavior.
All this to say, I think what you are describing is normal.
All this to say, I think what you are describing is normal.
