My 98 Maxima Se fan for hvac has been slowing down and the ramping back up. Any ideas?

 

Check the resistor for the settings. Fan speed issues are almost always a failing resistor.

 

It seems like most people whose fan only works on high and not on the first three speeds have to change out the resistor. My fan is working on all speeds but keeps slowing up and down. Could it still be the resistor?

The resistor does look easy to change at least.

 

Auto or Manual climate control?

Manual, most likely the resistor, could be the motor failing.
If your Auto it's likely the amplifier.

 

Regardless of which style of controls, I think it is the blower motor, the bushings drying out.

 

It is manual climate control.