One problem related to crankcase (pcv) has been reported for the 1996 Buick Regal. The most recently reported issues are listed below.
Vehicle back fire through the intake and smoke rolls out from under the hood when trying to start the vehicle, normally start good after sitting over night, but go to start it again it will back fire or the engine idle is very erratic before it will smooth out. I replace spark plug, spark plug wires, cam sensor, pcv valve, fuel filter check battery connection.