Or search: vomit, puking, reflex, emesis, ejection, expulsion, projection, rumination, hematemesis, hyperemesis, disgorgement, regurgitation
2 Syllables: SU
broadening, jostling, modeling, offering, quarreling, softening
3 Syllables: SUU
auditing, blossoming, bothering, competence, competent, fostering, gossiping, honoring, honouring, modelling, profiting, promising, prospering, slaughtering, tottering, watering
4 Syllables: USUU
preponderating

Found 23 words across 3 groupings. Skipped 1 excess word of a similar stem.