Pre mature gear change on 2003 Mercedes-Benz E320

I noticed since few days that my car changing gear earlier than it it should be. on a normal drive 2nd gear changes at 15KM speed, 3rd gear at 35, 4th gear at 50 KM speed. Is it normal?
Alo, my car lost power. it takes very long time to get to 100 speed. I am thinking to change air and fuel filter.
Any one can help what should I do?.
Thank You.

Asked by for the 2003 Mercedes-Benz E320
possibly fluid low.