Certainly there were widespread food shortages in 1988 following a drop in agricultural production, high inflation and significant unemployment. The situation in the northern provinces has often been described as famine, though there are few statistics about how many people died. The only numbers I could find was from the following Asian Bulletin [Vol 13, p81, 1988] article:
"On July 9, [Vietnamese newspaper] Tuoi Tre, was reported as having said 21 Vietnamese had starved to death because of food shortages in the northern part of the country. The report said hunger plagued 10 million people in northern provinces. Four million people, especially in Thanh Hoa province, faced severe hunger, and 21 people had starved to death. Tuoi Tre said the first public disclosure of famine deaths was made in Ho Chi Minh City by delegates who attended a June 23-28 session of the National Assembly."
The food shortages resulted in major economic changes in Vietnam, led by Communist reformists. By 1989, Vietnam was apparently the third-largest rice exporting country in the world [James Elliott, The Future of Socialism, p133].