 Put it in neutral, put it back in gear, and then it'd go again. That might be what's going on, but I wonder if there's not something wrong with that throttle body. And there may even be some codes hidden in the system. Not enough to turn that light on yet, but if you were to scan it, you might be able to find some history codes or even some permanent codes that are hiding out in there that are just not turning on that check engine light.