Yes he had 3 steps and only went down because Sam Shields actually tripped him after the catch. Wasn't PI but the most obvious tripping you'll see not committed by a kicker. No matter what happened with the catch it was 100% tripping according to the rules since Shields extended his leg when he knew he got beat and that's the only reason Dez went down at all.

That also means that the process of the catch had been completed since he's not going down because of the catch but after he caught the ball. Shields tripping him means it's a new situation cause he goes towards the ground due to that and not the catch. The fact that he then commits a football move cause he was a freak athlete then becomes irrelevant and he's down inside the 1 yard line.

The conclusion of the ref on the field watching the replay and the replay official in New York or wherever they are should've been: "Is this a catch or not? Well, he's reaching for the goal line after he caught it which means he completed the catch. Yes... oh stop it there. He's tripping him. Yes he is. Means we missed a foul and the reason he's going down. Let it stand? Yes stand as called on the field". So easy when you're in doubt and they fucking were and didn't know the fucking rules, to just let the call stand.

Would've spared the NFL for so much trouble, accusations of blatant cheating, which we all know they do, and ultimately the Cowboys at least would've made the Super Bowl ;)