According to Studebaker Service Bulletin No. 317 for 1956, it states the the top cover gasket may not be sealing. This allows fuel to flood the engine from around the choke passage hole and idle tube cross-over passages. This results in a rich mixture, which may stall the engine. It suggests examining the gasket, to see if the rib which runs all the way around the cover is leaving an imprint. It suggests trying another gasket (P/N 537189), but cutting out the center section. If you still cannot get full contact, it said to try two gaskets. Tighten the center screws first and make sure all screws are tight.