Fan speed oscilates up and down. Normal at low RPM?
 

I notice it more when I just turn the car on and in normal idle. When I press the gas the fan speed becomes normal.

Thanks.

Can I take it you are talking about the ac/heat blower fan? Or are you talking about one of the engine fans...

If you are talking about the ac blower fan I'd say the ilkely culprit is the final stage resistor as it is the most common fail point and causes what you are describing. Just a search of final stage resistor or FSR will pull up dozens of threads on them failing.