Knowing that the mic is on triggers your stuttering behavioral pattern. One tennis player got a block that whenever the judge said 40-40, he always lost that game. Body tensing up, serve in the net, trembling legs, mind everywhere. The whole package. He put in earplugs so he wouldn't hear it. In the beginning it was terrifying, playing even worse. But after a while it neutralized and he could play more relaxed. It is useful to experiment like this and try to find those triggers and put even more force into them. To be able to put in earplugs (mute) gives makes you play relaxed. It is no easy thing, but try to examine your whole body when this trigger happens. As in tennis, a tense body (tounge, shoulders etc.) Makes the whole motion weird. Experiment with the triggers and try to cope with them in time. One good part of more fluent speech. Best of luck, hope it gives some inspiration at least :)