Toroidicity-induced drift modes are investigated in the strongly collisional regime. Ion magnetic drift resonant effects are fully retained, also in the ion sound contribution. The lowest even mode becomes unstable due to the electron-ion collisions. When the perpendicular viscosity (ion-ion collisions) is taken into account in the perturbed ion density, the growth rate exhibits a maximum instead of growing without bound for increasing kperpendicular to rho i. It is shown that, for these modes, the ion perpendicular viscosity is more important than the effect on the ion response of the friction between the ions and the electrons.