Same word as vacillate:

alternate, be indecisive, be irresolute, change, change mind, dither, fence-straddle, fluctuate, hedge, hem and haw, hesitate, hover, oscillate, pause, pussyfoot around, reel, rock, run hot and cold, seesaw, shilly-shally, stagger, straddle, sway, swing, waffle, waver, whiffle, yo-yo