Storks are accomplished soarers, but they use it as a method to travel long distances rather than to forage. That's done on foot.

Several sources I've found, including Hancock, Kushlan & Kahl, Storks, Storks, Ibises and Spoonbills of the World disagree with you, saying that they are primarly scavengers and opportunistic feeders with large numbers seemingly "appearing out of nowhere" at locust swarms, grass fires and citing an example of over 200 Marabous at a single elephant carcass. Several times it is pointed out that carrion is an important part of the diet. The book says Marabous are frequently associated with Vultures and can often be found in "big game country" at kills of large predators, where it opportunistically waits for Vultures to cut pieces of flesh off with their hooked bills which they then steal. It cuts back on scavenging and forages for living prey during the breeding season when they stick more to wetlands rather than to the open plains where they're found outside of the breeding season. The book posits that this is because the fast growing young need calcium in this season.