95 discovery dies

My 95 discovery dies when you take your foot off the acelerator in a turn under 30mph. This happens only occasionally but now more frequently than ever before. It will perform fine for several days and then start it again. I thought it was when the gas level got low but started paying attention and found that it is at any gas level. The repair shop put a gas additive in the tank and that seemed to help for a half a tank but it started again. Anyone got any idea what is causing this? It use to happen only when I took the car to the dealer for a tune up. After the first 3 times I learned to start the car in their lot and drive around for a minute or two before venturing out. It never failed that the car would die so I would roll back up to the service department and they would take it back in for a few minutes and return it without appology. I quit going to the dealer and my independent shop now gets it right.