1994 Oldsmobile Cutlass sputtering

Engine Mechanical problem
1994 Oldsmobile Cutlass 6 cyl Automatic

This is my niece's car. When you start it, it sputters/coughs like it will go dead but it does not. The sputtering does not seem to have any effect on the running and it will go up a hill with no problem as if the sputtering is gone. The computer has been replaced but did not help the sputtering/coughing.

Thanks for any help yu can give.