I am certain that AMC did not show the full extended cut. If they did, someone else would have mentioned it; everything talking about that marathon was about the fact that Superman II was the Donner cut. Nobody ever said anything of the first film being the KCOP cut.

My guess is that they showed the 151-minute extended restored version from 2001, which had a few of the additional scenes put back in. Thus, you'd remember things like Superman going through Luthor's gauntlet.

Most of the deleted scenes have never even been released as extras on DVD/Blu-ray, I just cannot believe it was the full 3-hour TV cut remastered. For one thing, it would have only had 22 minutes of commercials for a 3 1/2 hour timeslot. No way would they put in that few ads.

On the other hand, I would absolutely believe AMC running a 2 1/2 hour movie with an hour of commercials.