vacillate
     v 1: be undecided about something; waver between conflicting
          positions or courses of action; "He oscillates between
          accepting the new position and retirement" [syn: {hover},
           {vibrate}, {oscillate}]
     2: move or sway in a rising and falling or wavelike pattern;
        "the line on the monitor vacillated" [syn: {fluctuate}, {waver}]
Source: WordNet® 2.0