vacillate

verb2

1. •
   To sway unsteadily from one side to the other; oscillate.

   • Its [the barometer's] normal register in the Paumotus [the Tuamotus] was 29.90, and it was quite customary to see it vacillate between 29.85 and 30.00, or even 30.05; […] — 1910
2. •
   To swing indecisively from one course of action or opinion to another.

   • Though it is vital to be alert for circumstances which require a change of plan, it is fatal to vacillate. — 1944