Faltered, past participle of falter. Synonyms in the same form.
Stammer
stammered, hesitated, stuttered, sticked, demurred, hawed, boggled, scrupled, halted
Stumble
stumbled, bumbled, staggered
Waver
wavered, trembled, tottered, vacillated, wobbled, quivered, reeled, fluttered
Other
failed, floundered
All synonyms for falter →