My 1993 Nissan Sentra GXE 1.6 engine has a fluctuating idle speed with occasional staling. I have replaced the plugs, wires, distributor cap & rotor, and fuel filter. I have tried injector cleaners and water removal gas additives.

Have you checked your MAF? Sentra's are famous for them having problems, I havent had an issue with mine yet thank god.

hi!try cleaning the throttle body and the stepper motor.i had the same problem with my car. use a carburetor cleaner to clean the throttlebody and the stepper motor.use a soft brush if necessary.spray the the throttle body and stepper motor with the carburetor cleaner.remove all the dirt inside and between the holes.let it dry and install it again.most likely your idle will be stable.im a mechanic and i did those steps on many nissan cars.try it.its a lot cheaper.

Sound to me like you have a vaccum leak. not very common on your car to have an intake gasket leak, but it's possible. get some carb cleaner in spray can and spray it all over the fuel injectors as the car is at idle and listen for any changes in running/idling. If the car starts running smoother, than the car is sucking the carb cleaner into the engine resulting in better idle, which will indicate a vaccum leak.

The problem turned out to be the Air Flow Sensor. The technician I had review my initial findings tried removing the air cabin before the sensor and blowing through the channel with an air hose. In doing this, the fluctuating idle or engine missing went away. Replacing the MAF did the trick.