It's hard to fault someone who sings with such a burnished voice, such pointed rhythm, and such utter sincerity. Still, your attention might wander midway through this third solo album the first since 1985 by the former lead singer of the Doobie Brothers. McDonald worked with four producers, in styles ranging from rock to funk, covering a wider musical range than ever before. But his earnest tone rarely changes, not even when he abandons his recurrent examination of difficult but optimistic love to explore, in ''Homeboy,'' why poor black kids might feel they have to join gangs. Only the five slower songs, among them the title track, rise a bit above the rest. In these McDonald's voice sounds darker, and he seems even more earnest which from a less honest artist might be too much of a good thing, but from McDonald actually registers as a mild but welcome change of pace.