Why hire a full-time executive when you can just rent one? More and more companies are turning to interim execs to fill gaps in leadership and expertise. They ride into town, close down a division or oversee an acquisition, then move on. Just don’t call them temps. Interim executives, according to those in the field, are professional problem solvers who “make something happen,” says Robert M. Kuhn, partner in charge of North American Operations for EIM.