My oil pressure gauge drops and shoots back up a few times until it warms up, it used to just do it in the winter now it does it even in the summer so I think I'm gonna change the pump and flush the motor to be safe how hard is it to change, how do you change it, and is the standard melling oil pump from autozone a good replacement, your collective thoughts are appreciated

 

i would get motorcraft or use an the oe part that ford does. and stay out of autozone. oriellys and a line can get dealer parts usually.

 

As dependant as these engines are on oil pressure, i would not settle for an economy part. My preference would be a stock or i would be more likely choose a performance part.
Have you checked your oil pressure sensor?