It happened to me as well, one of the scariest moments ever! About 5 years ago I was at WOT on the autostrada near Bologna in 4th, lifted my foot off the pedal because of traffic ahead and nothing happened - I turned off the ignition key, then put in neutral and braked - started the car again while still rolling and all was good - but still sticky with a 3 second lag of deceleration . Drove to mechanic slowly - Brevaglieri replaced my entire throttle cable - it was rusty. Do not drive the car if the throttle does not return as it should. In my case there was not prior warning.