1989 Buick Century Hard to start when engine cold

Engine Mechanical problem
1989 Buick Century 6 cyl Front Wheel Drive Automatic

In the morning or when the engine is cold it is hard to start. It will start after the engine turns a dozen times which is not good for the starter. When I spray starter fluid in the intake it starts right up. After it starts and runs it runs great. When I stop and turn the motor off even for a half hour it will start right up. The engine runs no code but I replaced the oxygen sensor and temperature sensor anyway. Only after it sits long enough will it be hard to start.
I have no problem donating in the future if the service is sincere. I hope you understand.