Or search: vacillant, hesitation, indecision, fluctuation, vacillating, vacillation, irregularity, irresolution, unregularity, scintillation
2 Syllables: SU
hastening, labeling, rationing, straightening
3 Syllables: SUU
catering, Chamberlain, favoring, favouring, laboring, labouring, neighboring, neighbouring, tailoring, tapering
3 Syllables: USU
disabling, enabling
4 Syllables: USUU
awakening, endangering, occasioning, unwavering

Found 20 words across 4 groupings.