No I didn't see the sequel. Michael Mann was inspired by Jean-Pierre Melville, who directed two EXCELLENT Neo-Noir films, that are among the greatest crime related films ever: Le Samourai and Le Cercle Rouge.

Heat definitely has Noir elements, but the thing is Neo-Noirs have evolved in style somewhat with different visuals. Collateral for instance, has Neo-Noir elements, more then Heat somewhat. Memento's noir feel is in the B/W scenes/narration.

As for Pulp Fiction, it isn't a Film-Noir.