Carr is the real deal, their running game is the real deal, and Houston has a decent Defense ... so how can Johnson not be the real deal?
Okay, so he's performing as a middle of the pack #2 WR in fantasy instead of the projected low #1 - that's nothing to sneaze at.
With a lesser QB, I might worry about the lack of receiving talent around Johnson, but Carr has the strength and guts to get the ball to Andre.
Carr/Johnson is certainly proving much better this season than the highly touted Pennington/Moss duo, and with Minnesota in his immediate future, Johnson is a must-play next week. After that he has a bye and a couple of decent defenses to go against, but the league's WRs seem to be holding up well against the better defenses so far.
FF is about consistency (unless you're experimenting and trying some probably-doomed matchup team) and Johnson is proving to be a consistent performer. Lack of other receiver options makes him the main target, which is what you want. The guys who gets the looks and the carries are the most likely to perform on a weekly basis.
Keep Johnson unless you can negotiate one heck of a deal for him. And start him.