Synonyms for Falter (same or very similar meaning)
WordNet sense 1 (be unsure or weak):
waverWordNet sense 2 (walk unsteadily):
bumble, stumbleWordNet sense 3 (the act of pausing uncertainly):
faltering, hesitationWordNet sense 4 (speak haltingly):
stammer, stutterFrom the ODE community, based on WordNetadd/edit