1988 Buick Skylark starts and shuts off

Engine starts fine and injector is spraying fuel. Injector then stops spraying fuel and engine dies. Just as engine dies it sprays fuel again. Ive replaced all sensors/controllers o2, heated air intake, map, throtle position, air idle valve, oil psi switch, water temp, cam position, ignition control module, and the ecm but not the prom. Checked fuel pressure reg it looks good and the injector seems to spray fine. Its seems as if the ecm is turning the injector off due to a rich fuel mix and then when the engine starts to die it turns it back on but not quick enough.