[Mumriken]

Did he actively, intentionally continue to pursue Morgoth's cause? Did he desire to further Morgoth's plans for Morgoth's sake rather than his own?

Morgoth's beyond any help, even if there was a point in pursuing "Morgoth's cause" whatever you mean by that....actually what do you mean by saying that. I think Sauron did a pretty good job in messing with the children of illuvatar. He did it because it's in his nature to do it, did he do it for morgoth? That is like saying did Gandalf show fireworks to little hobbit children because of Manwe wanting him to do so. Sauron did what he did because that is who he is. Being loyal means that he is on Morgoth's side. If he wouldn't be loyal he would go back to valinor and be judged and maybe be turned back into a good guy again. He never did therefore he is loyal. I don't get this "morgoth's sake". A soldier in a army doesn't fight because the general tells him to do so, he fights because he wants to.

With Morgoth out of the picture he was furthering his own goals, pursuing his own agenda, and the only allegiance he owed was to himself. He was now his own master, not the obedient servant he had been in the First Age, and all the times he exploited the memory of Morgoth and the products of his reign (Orcs and the like) were for the sake of his own power and dominion, not about trying to bring Morgoth's thwarted schemes to fruition.
If there is evidence to the contrary I would of course be very interested to read it!

The evidence to the contrary is that Sauron and Morgoth were very much alike in thought. Morgoth was thrown out of Arda chained unable to do anything. Sauron could do nothing but to keep doing what he did before, what HE IS. He could do nothing but do it for his own sake. Morgoth was out of the picture, if Morgoth would be in the world Sauron would join him again as a servant WHO LOVES TO SERVE because his master's goals are his own.

EDIT:So change the wikipedia article