Sounds similar to a problem we had on a Shogun Pinin. The throttle valve controlled by a stepper motor had partially seized to the point it was intermittently jamming in a certain position, hence unable to respond to ECU commands. Symptoms were high idle speed then little or no power as clutch let in.

New one was £350 + VAT exchange BTW!

Richard

2018 Roadster 3.7
1966 Land Rover S2a 88
2024 Royal Enfield Guerrilla 450
1945 Guzzi Airone